Code
P1193
BMW
P — Powertrain
Post-Catalyst Fuel Trim System Bank 2
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
DAEWOO
P — Powertrain
ETS LIMPHOME RPM -LOW
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
DODGE
P — Powertrain
Inlet Air Temp Circuit High
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
FORD
P — Powertrain
EGR Drive Overcurrent
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
JAGUAR
P — Powertrain
O2 Sensor Heater Circuit Open, Inferred Fault
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
JEEP
P — Powertrain
Inlet Air Temp. Circuit High
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
LAND ROVER
P — Powertrain
Heated oxygen sensor circuit open, inferred failure (banks 1 and 2 of sensor 2)
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Repair manuals
Manual library for LAND ROVER
320
Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
LAND ROVER
-
LAND ROVER: 2022
-
Defender
- 90
- 90
- 90 S
- 90 S
- 90 V8
- 90 V8
- 90 V8 Carpathian Edition
- 90 V8 Carpathian Edition
- 90 X
- 90 X
- 90 X-Dynamic HSE
- 90 X-Dynamic HSE
- 90 X-Dynamic S
- 90 X-Dynamic S
- 90 X-Dynamic SE
- 90 X-Dynamic SE
- 110
- 110
- 110 S
- 110 S
- 110 SE
- 110 SE
- 110 V8
- 110 V8
- 110 V8 Carpathian Edition
- 110 V8 Carpathian Edition
- 110 X
- 110 X
- 110 X-Dynamic SE
- 110 X-Dynamic SE
- 110 XS Edition
- 110 XS Edition
-
Discovery
- R-Dynamic HSE
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2022: Discovery R-Dynamic S
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2022: Discovery R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Discovery R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Discovery R-Dynamic S
- S
- S
-
Discovery Sport
-
Range Rover
- Autobiography, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover Autobiography
- Autobiography, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover Autobiography
- 2022 Range Rover Base
- 2022 Range Rover Base
- First Edition
- First Edition
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover HSE Westminster
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover HSE Westminster
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover SE
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover SE
- SE, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover SE
- SE, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover SE
- SV
- SV
- SVAutobiography
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic
- SVAutobiography Dynamic Blk.
- SVAutobiography Dynamic Blk.
-
Range Rover Evoque
-
Range Rover Velar
- R-Dynamic HSE
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2022: Range Rover Velar R-Dynamic S
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2022: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover Velar R-Dynamic S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2022: Range Rover Velar S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2022: Range Rover Velar S
- S, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover Velar S
- S, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover Velar S
-
-
LAND ROVER: 2021
-
Discovery
- R-Dynamic HSE
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2021: Discovery R-Dynamic S
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2021: Discovery R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Discovery R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Discovery R-Dynamic S
- S
- S
-
Discovery Sport
-
Range Rover
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Autobiography
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Autobiography
- Autobiography Fifty Edition
- Autobiography Fifty Edition
- 2021 Range Rover Base
- 2021 Range Rover Base
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover HSE
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover HSE
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover HSE Westminster
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover HSE Westminster
- SVAutobiography
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic
- SVAutobiography Dynamic Blk.
- SVAutobiography Dynamic Blk.
-
Range Rover Evoque
-
Range Rover Sport
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography Dynamic
- HSE Dynamic
- HSE Dynamic
- HSE Silver Edition, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Sport HSE Silver Edition
- HST
- HST
- SE
- SE
- SVR
- SVR
- SVR Carbon Edition
- SVR Carbon Edition
-
Range Rover Velar
- R-Dynamic HSE
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2021: Range Rover Velar R-Dynamic S
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2021: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Velar R-Dynamic S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2021: Range Rover Velar S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2021: Range Rover Velar S
- S, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Velar S
- S, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Velar S
-
LAND ROVER: 2020
-
Defender
- 90 First Edition
- 90 First Edition
- 110 First Edition
- 110 First Edition
- 110 HSE
- 110 HSE
- 110 S
- 110 S
- 110 SE
- 110 SE
- 110 X
- 110 X
- 110, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Defender 110
- 110, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Defender 110
- 110, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Defender 110
- 110, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Defender 110
-
Discovery
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE
- HSE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE
- HSE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE
- HSE Luxury, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE Luxury
- HSE Luxury, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE Luxury
- HSE Luxury, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE Luxury
- HSE Luxury, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE Luxury
- Landmark
- Landmark
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery SE
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery SE
- SE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery SE
- SE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery SE
-
Range Rover
- Autobiography
- Autobiography
- Base, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Base
- Base, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Base
- Base, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Base
- Base, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Base
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover HSE
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover HSE
- SVAutobiography
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic
-
Range Rover Evoque
-
Range Rover Sport
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport Autobiography Dynamic
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport HSE
- HSE Dynamic
- HSE Dynamic
- HSE PHEV
- HSE PHEV
- HST
- HST
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport SE
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport SE
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport SE
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport SE
- SVR
- SVR
-
Range Rover Velar
- R-Dynamic HSE
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar R-Dynamic S
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar R-Dynamic S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar S
- S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar S
- S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar S
- SVAutobiography Dyn.
- SVAutobiography Dyn.
-
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Code
P1193
LINCOLN
P — Powertrain
EGR Drive Overcurrent
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Repair manuals
Manual library for LINCOLN
166
Browse 166 LINCOLN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
LINCOLN
-
LINCOLN: 2024
-
LINCOLN: 2023
-
LINCOLN: 2022
-
LINCOLN: 2021
-
LINCOLN: 2020
-
Continental
- Base, AWD
- Base, FWD
- Black Label, 2.7L Eng VIN P · 2.7L Eng VIN P2020: Continental Black Label
- Black Label, 3.0L Eng VIN C · 3.0L Eng VIN C2020: Continental Black Label
- Livery, AWD
- Livery, FWD
- Reserve, 2.7L Eng VIN P, AWD
- Reserve, 2.7L Eng VIN P, FWD
- Reserve, 3.0L Eng VIN C · 3.0L Eng VIN C2020: Continental Reserve
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Code
P1193
MERCURY
P — Powertrain
EGR Drive Overcurrent
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Repair manuals
Manual library for MERCURY
296
Browse 296 MERCURY manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
MERCURY
-
MERCURY: 2011
-
MERCURY: 2010
-
Mountaineer
-
MERCURY: 2009
-
Mountaineer
-
MERCURY: 2008
-
Mountaineer
-
MERCURY: 2007
-
Montego
-
Monterey
-
Mountaineer
-
MERCURY: 2006
-
Montego
-
Monterey
-
Mountaineer
-
MERCURY: 2005
-
Grand Marquis
-
Mariner
-
Montego
-
Monterey
-
Mountaineer
-
-
MERCURY: 2004
-
Marauder
-
Monterey
-
Mountaineer
-
MERCURY: 2003
-
Marauder
-
Mountaineer
-
MERCURY: 2002
-
Cougar
-
Mountaineer
-
Sable
-
Villager
-
-
MERCURY: 2001
-
Mountaineer
-
Sable
- GS, 4D Sedan, 3.0 2, 4F50N
- GS, 4D Sedan, 3.0 2, AX4S
- GS, 4D Sedan, 3.0 S
- GS, 4D Sedan, 3.0 U, 4F50N
- GS, 4D Sedan, 3.0 U, AX4S
- GS, 4D Wagon, 3.0 2, 4F50N
- GS, 4D Wagon, 3.0 2, AX4S
- GS, 4D Wagon, 3.0 U, 4F50N
- GS, 4D Wagon, 3.0 U, AX4S
- LS, 4D Sedan, 3.0 2
- LS, 4D Sedan, 3.0 S
- LS, 4D Sedan, 3.0 U, 4F50N
- LS, 4D Sedan, 3.0 U, AX4S
- LS, 4D Wagon, 3.0 S
- LS, 4D Wagon, 3.0 U, 4F50N
- LS, 4D Wagon, 3.0 U, AX4S
-
Villager
-
MERCURY: 2000
-
Cougar
-
Mountaineer
-
Villager
-
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Code
P1193
Other
P — Powertrain
EGR Drive Overcurrent
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
PLYMOUTH
P — Powertrain
Inlet Air Temp Circuit High
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Code
P1193
PONTIAC
P — Powertrain
Inlet Air Temp Circuit High
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
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Was this AI description helpful?
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Code
P1193
RAM
P — Powertrain
IAT Circuit High
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Your experience will help others
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Was this AI description helpful?
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Code
P1193
SCION
P — Powertrain
Fuel rail pressure sensor circuit malfunction
AI status
Completed
Completed
100%
Causes
- Faulty downstream (post‑catalyst) oxygen sensor — Bank 2 (Sensor 2)
- Damaged wiring, corroded connector, or poor ground to downstream O2 sensor
- Exhaust leak upstream of the downstream sensor or at the manifold/cat flange
- Catalytic converter degraded, clogged or inefficient on Bank 2
- Fuel system issues (incorrect fuel pressure, leaking injector) affecting trims
- Vacuum leak or intake air leak affecting long‑term fuel trim
Symptoms
- Check Engine Light (MIL) illuminated
- Possible poor fuel economy
- Failed emissions test (high HC/NOx/CO)
- Occasional rough running or hesitation under load (if fuel trim is heavily affected)
- Freeze frame data showing abnormal post‑cat O2 or fuel trim values
What to check
- Read/record stored codes and freeze‑frame data with a capable scan tool
- Visually inspect Bank 2 downstream O2 sensor connector and wiring for damage or corrosion
- Compare live data: upstream (pre‑cat) O2 sensor vs downstream (post‑cat) O2 sensor signals
- Check short‑term and long‑term fuel trims (STFT/LTFT) for Bank 2
- Verify O2 sensor heater operation and heater circuit resistance/voltage per BMW specs
- Perform exhaust leak check (visual, smoke, or pressure test) upstream of post‑cat sensor
Signal parameters
- Upstream (pre‑cat) narrowband O2 (Bank 2 Sensor 1): switching/highly variable ~0.1–0.9 V during closed‑loop
- Downstream (post‑cat) O2 (Bank 2 Sensor 2): should be relatively steady near stoichiometric (~0.4–0.6 V) with low switching if catalyst is working
- If downstream tracks upstream (rapid switching 0.1–0.9 V) → catalyst likely inefficient
- Typical downstream O2 voltage variation expected < ~0.1–0.2 V in steady state when catalyst is healthy
- Heater circuit resistance/operation: consult BMW spec (verify heater voltage/current and element resistance with sensor disconnected)
- Normal fuel trims: short‑term trims usually within ±10%; long‑term trims typically within ±10–15% (significant deviation suggests fuel or air leak issues)
Diagnostic algorithm
- Record freeze‑frame and full trouble code list. Confirm P1193 is current or historic and note conditions when set.
- Perform a visual inspection of Bank 2 downstream O2 sensor connector, wiring harness, and engine/exhaust area for damage, contamination, or leaks.
- With a scan tool, view live data for Bank 2: compare upstream (Sensor 1) vs downstream (Sensor 2) O2 voltages and observe fuel trims (STFT/LTFT).
- Verify downstream sensor heater operation (voltage present, correct current) and measure heater resistance per BMW spec. Repair any heater circuit faults.
- If downstream sensor shows rapid switching similar to upstream, perform catalyst efficiency test: monitor oxygen sensor response and/or use a scan tool catalyst monitor (if available).
- Check for exhaust leaks between the catalytic converter and the downstream O2 sensor (smoke test or visual inspection). Repair leaks before replacing sensors.
- Test fuel system: measure fuel rail pressure and inspect injectors for leaks or malfunctions that could affect trims.
- If fuel system and wiring are good but downstream still indicates poor catalyst performance, measure exhaust backpressure to check for clogged converter.
- Replace the downstream O2 sensor if it fails electrical or response tests. After repair, clear codes and perform a full drive cycle to confirm the fault is resolved.
- If fault persists after sensor replacement and wiring/cats checked, consider ECU software update or professional advanced diagnostics.
Likely causes
- Contaminated or failing Bank 2 post‑cat O2 sensor
- Wiring harness chafing, connector corrosion, or broken sensor heater circuit
- Catalyst on Bank 2 has lost efficiency (allowing downstream O2 to follow upstream)
- Exhaust leak between catalytic converter and downstream O2 sensor
- Sustained fuel pressure too high or too low causing abnormal fuel trim
- Significant vacuum leak or internal engine issue changing fuel trims
Fault status
Status
Post‑catalyst fuel trim system — Bank 2. Downstream oxygen sensor/catalyst efficiency or related wiring is outside expected range.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Your experience will help others
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Was this AI description helpful?
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