Code
P1193
BMW
P — Powertrain
Post-Catalyst Fuel Trim System Bank 2
Views:
UK: 20
EN: 35
RU: 18
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
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Code
P1193
DAEWOO
P — Powertrain
ETS LIMPHOME RPM -LOW
Views:
UK: 3
EN: 8
RU: 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
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Code
P1193
DODGE
P — Powertrain
Inlet Air Temp Circuit High
Views:
UK: 23
EN: 40
RU: 21
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
Views:
UK: 17
EN: 33
RU: 21
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
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Code
P1193
JAGUAR
P — Powertrain
O2 Sensor Heater Circuit Open, Inferred Fault
Views:
UK: 16
EN: 31
RU: 19
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
Views:
UK: 16
EN: 32
RU: 18
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)
Views:
UK: 5
EN: 10
RU: 7
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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Workshop ManualYour experience will help others
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Code
P1193
LINCOLN
P — Powertrain
EGR Drive Overcurrent
Views:
UK: 20
EN: 40
RU: 21
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
MERCURY
P — Powertrain
EGR Drive Overcurrent
Views:
UK: 15
EN: 38
RU: 18
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
Other
P — Powertrain
EGR Drive Overcurrent
Views:
UK: 21
EN: 33
RU: 22
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
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Code
P1193
PLYMOUTH
P — Powertrain
Inlet Air Temp Circuit High
Views:
UK: 28
EN: 90
RU: 30
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
Views:
UK: 17
EN: 33
RU: 17
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
RAM
P — Powertrain
IAT Circuit High
Views:
UK: 1
EN: 6
RU: 1
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
Views:
UK: 0
EN: 6
RU: 1
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
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