Code
P0157
Generic
P — Powertrain
O2 Sensor Circuit Low Voltage Bank 2 Sensor 2
Views:
UK: 19
EN: 35
RU: 32
AI status
Completed
Completed
100%
Causes
- Failed downstream O2 sensor (Bank 2 Sensor 2)
- Damaged, corroded, or disconnected sensor connector or wiring
- Short to ground on the O2 sensor signal circuit
- Exhaust leak upstream of the sensor or damaged exhaust piping
- Contaminated sensor (oil, coolant, silicone, sulfur)
- PCM fault (rare)
Symptoms
- Check Engine MIL illuminated
- Possible failed emissions test
- Usually no obvious drivability problems; sometimes reduced fuel economy
- Possible stored freeze-frame data showing low sensor voltage
What to check
- Scan for P0157 and related freeze-frame/fault history; note conditions when set
- Inspect sensor and connector at bank 2 sensor 2 for corrosion, contamination, or physical damage
- Visually inspect wiring harness for chafing, pinched wires, or melted insulation
- Use scan tool to view live PID for B2S2 voltage and compare to upstream sensor (B2S1) behavior
- Backprobe signal wire with key on (engine off) and with engine running to check voltage
- Check for a short to ground on the signal wire with multimeter (continuity to chassis)
Signal parameters
- Downstream O2 sensor (Sensor 2) expected to be relatively stable near ~0.45 V; not rapidly switching like upstream
- Low-voltage condition commonly defined as sensor signal below ~0.1 V or significantly lower than expected steady voltage
- Upstream (Sensor 1) typically oscillates ~0.1–0.9 V; downstream should be steady near mid-voltage if cat working
- Heater circuit voltage: typically battery voltage (approx. 10–14 V) when key on/run; heater resistance varies by sensor type (check OEM specs)
Diagnostic algorithm
- Verify code with a scan tool and record freeze-frame data and related codes (look for upstream O2 and catalytic codes).
- Inspect B2S2 connector and wiring for corrosion, damage, poor pins, or disconnection. Repair as needed.
- With ignition off, check continuity from the sensor signal pin to the PCM signal pin; verify no short to chassis ground and correct resistance to PCM (compare to wiring diagram).
- With key on (engine off) backprobe the signal terminal to check reference/idle voltage and ground integrity. Start engine and observe live voltage: downstream should be near mid-range (not stuck low).
- Compare B2S2 to B2S1 (upstream) and to B1 sensors; if upstream oscillates normally and downstream is low, suspect sensor or wiring for B2S2 or catalytic converter issues.
- Check heater circuit: verify heater supply voltage and ground, and measure heater resistance. A failed heater may not set P0157 directly but indicates sensor failure.
- Inspect for exhaust leaks or damage upstream of the sensor; repair leaks then retest.
- If wiring and connectors check good, replace the B2S2 oxygen sensor with OE or quality aftermarket unit.
- Clear codes and perform a drive cycle to confirm the code does not return. If code returns and wiring checked, consider PCM or deeper intermittent wiring harness faults.
Likely causes
- Open or shorted signal wire / poor connector ground between bank 2 sensor 2 and PCM
- Failed O2 sensor (worn or contaminated downstream sensor)
- Corroded connector causing low or intermittent signal
- Exhaust leak between exhaust port and sensor causing erroneous readings
Fault status
Status
O2 Sensor Circuit Low Voltage — Bank 2 Sensor 2. The downstream oxygen sensor signal is reporting an abnormally low voltage; check sensor, wiring/connectors, and exhaust integrity.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop ManualAudi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop ManualAUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop ManualAudi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop ManualAudi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop ManualAudi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop ManualAudi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop ManualAudi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop ManualAudi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop ManualAudi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop ManualAudi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop ManualLAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
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Code
P0157
GWM
P — Powertrain
- Oxygen sensor circuit low voltage (bank 2, sensor 2)
Views:
UK: 4
EN: 3
RU: 9
AI status
Completed
Completed
100%
Causes
- Failed downstream O2 sensor (Bank 2 Sensor 2)
- Damaged, corroded, or disconnected sensor connector or wiring
- Short to ground on the O2 sensor signal circuit
- Exhaust leak upstream of the sensor or damaged exhaust piping
- Contaminated sensor (oil, coolant, silicone, sulfur)
- PCM fault (rare)
Symptoms
- Check Engine MIL illuminated
- Possible failed emissions test
- Usually no obvious drivability problems; sometimes reduced fuel economy
- Possible stored freeze-frame data showing low sensor voltage
What to check
- Scan for P0157 and related freeze-frame/fault history; note conditions when set
- Inspect sensor and connector at bank 2 sensor 2 for corrosion, contamination, or physical damage
- Visually inspect wiring harness for chafing, pinched wires, or melted insulation
- Use scan tool to view live PID for B2S2 voltage and compare to upstream sensor (B2S1) behavior
- Backprobe signal wire with key on (engine off) and with engine running to check voltage
- Check for a short to ground on the signal wire with multimeter (continuity to chassis)
Signal parameters
- Downstream O2 sensor (Sensor 2) expected to be relatively stable near ~0.45 V; not rapidly switching like upstream
- Low-voltage condition commonly defined as sensor signal below ~0.1 V or significantly lower than expected steady voltage
- Upstream (Sensor 1) typically oscillates ~0.1–0.9 V; downstream should be steady near mid-voltage if cat working
- Heater circuit voltage: typically battery voltage (approx. 10–14 V) when key on/run; heater resistance varies by sensor type (check OEM specs)
Diagnostic algorithm
- Verify code with a scan tool and record freeze-frame data and related codes (look for upstream O2 and catalytic codes).
- Inspect B2S2 connector and wiring for corrosion, damage, poor pins, or disconnection. Repair as needed.
- With ignition off, check continuity from the sensor signal pin to the PCM signal pin; verify no short to chassis ground and correct resistance to PCM (compare to wiring diagram).
- With key on (engine off) backprobe the signal terminal to check reference/idle voltage and ground integrity. Start engine and observe live voltage: downstream should be near mid-range (not stuck low).
- Compare B2S2 to B2S1 (upstream) and to B1 sensors; if upstream oscillates normally and downstream is low, suspect sensor or wiring for B2S2 or catalytic converter issues.
- Check heater circuit: verify heater supply voltage and ground, and measure heater resistance. A failed heater may not set P0157 directly but indicates sensor failure.
- Inspect for exhaust leaks or damage upstream of the sensor; repair leaks then retest.
- If wiring and connectors check good, replace the B2S2 oxygen sensor with OE or quality aftermarket unit.
- Clear codes and perform a drive cycle to confirm the code does not return. If code returns and wiring checked, consider PCM or deeper intermittent wiring harness faults.
Likely causes
- Open or shorted signal wire / poor connector ground between bank 2 sensor 2 and PCM
- Failed O2 sensor (worn or contaminated downstream sensor)
- Corroded connector causing low or intermittent signal
- Exhaust leak between exhaust port and sensor causing erroneous readings
Fault status
Status
O2 Sensor Circuit Low Voltage — Bank 2 Sensor 2. The downstream oxygen sensor signal is reporting an abnormally low voltage; check sensor, wiring/connectors, and exhaust integrity.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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Code
P0157
HUMMER
P — Powertrain
Heated Oxygen Sensor (HO2S) Circuit Low Voltage Bank 2 Sensor 2
Views:
UK: 13
EN: 16
RU: 22
AI status
Completed
Completed
100%
Causes
- Failed downstream O2 sensor (Bank 2 Sensor 2)
- Damaged, corroded, or disconnected sensor connector or wiring
- Short to ground on the O2 sensor signal circuit
- Exhaust leak upstream of the sensor or damaged exhaust piping
- Contaminated sensor (oil, coolant, silicone, sulfur)
- PCM fault (rare)
Symptoms
- Check Engine MIL illuminated
- Possible failed emissions test
- Usually no obvious drivability problems; sometimes reduced fuel economy
- Possible stored freeze-frame data showing low sensor voltage
What to check
- Scan for P0157 and related freeze-frame/fault history; note conditions when set
- Inspect sensor and connector at bank 2 sensor 2 for corrosion, contamination, or physical damage
- Visually inspect wiring harness for chafing, pinched wires, or melted insulation
- Use scan tool to view live PID for B2S2 voltage and compare to upstream sensor (B2S1) behavior
- Backprobe signal wire with key on (engine off) and with engine running to check voltage
- Check for a short to ground on the signal wire with multimeter (continuity to chassis)
Signal parameters
- Downstream O2 sensor (Sensor 2) expected to be relatively stable near ~0.45 V; not rapidly switching like upstream
- Low-voltage condition commonly defined as sensor signal below ~0.1 V or significantly lower than expected steady voltage
- Upstream (Sensor 1) typically oscillates ~0.1–0.9 V; downstream should be steady near mid-voltage if cat working
- Heater circuit voltage: typically battery voltage (approx. 10–14 V) when key on/run; heater resistance varies by sensor type (check OEM specs)
Diagnostic algorithm
- Verify code with a scan tool and record freeze-frame data and related codes (look for upstream O2 and catalytic codes).
- Inspect B2S2 connector and wiring for corrosion, damage, poor pins, or disconnection. Repair as needed.
- With ignition off, check continuity from the sensor signal pin to the PCM signal pin; verify no short to chassis ground and correct resistance to PCM (compare to wiring diagram).
- With key on (engine off) backprobe the signal terminal to check reference/idle voltage and ground integrity. Start engine and observe live voltage: downstream should be near mid-range (not stuck low).
- Compare B2S2 to B2S1 (upstream) and to B1 sensors; if upstream oscillates normally and downstream is low, suspect sensor or wiring for B2S2 or catalytic converter issues.
- Check heater circuit: verify heater supply voltage and ground, and measure heater resistance. A failed heater may not set P0157 directly but indicates sensor failure.
- Inspect for exhaust leaks or damage upstream of the sensor; repair leaks then retest.
- If wiring and connectors check good, replace the B2S2 oxygen sensor with OE or quality aftermarket unit.
- Clear codes and perform a drive cycle to confirm the code does not return. If code returns and wiring checked, consider PCM or deeper intermittent wiring harness faults.
Likely causes
- Open or shorted signal wire / poor connector ground between bank 2 sensor 2 and PCM
- Failed O2 sensor (worn or contaminated downstream sensor)
- Corroded connector causing low or intermittent signal
- Exhaust leak between exhaust port and sensor causing erroneous readings
Fault status
Status
O2 Sensor Circuit Low Voltage — Bank 2 Sensor 2. The downstream oxygen sensor signal is reporting an abnormally low voltage; check sensor, wiring/connectors, and exhaust integrity.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
P0157
LAND ROVER
P — Powertrain
low circuit voltage of the sensor P215 (bank 2 sensor 2)
Views:
UK: 9
EN: 15
RU: 19
AI status
Completed
Completed
100%
Causes
- Failed downstream O2 sensor (Bank 2 Sensor 2)
- Damaged, corroded, or disconnected sensor connector or wiring
- Short to ground on the O2 sensor signal circuit
- Exhaust leak upstream of the sensor or damaged exhaust piping
- Contaminated sensor (oil, coolant, silicone, sulfur)
- PCM fault (rare)
Symptoms
- Check Engine MIL illuminated
- Possible failed emissions test
- Usually no obvious drivability problems; sometimes reduced fuel economy
- Possible stored freeze-frame data showing low sensor voltage
What to check
- Scan for P0157 and related freeze-frame/fault history; note conditions when set
- Inspect sensor and connector at bank 2 sensor 2 for corrosion, contamination, or physical damage
- Visually inspect wiring harness for chafing, pinched wires, or melted insulation
- Use scan tool to view live PID for B2S2 voltage and compare to upstream sensor (B2S1) behavior
- Backprobe signal wire with key on (engine off) and with engine running to check voltage
- Check for a short to ground on the signal wire with multimeter (continuity to chassis)
Signal parameters
- Downstream O2 sensor (Sensor 2) expected to be relatively stable near ~0.45 V; not rapidly switching like upstream
- Low-voltage condition commonly defined as sensor signal below ~0.1 V or significantly lower than expected steady voltage
- Upstream (Sensor 1) typically oscillates ~0.1–0.9 V; downstream should be steady near mid-voltage if cat working
- Heater circuit voltage: typically battery voltage (approx. 10–14 V) when key on/run; heater resistance varies by sensor type (check OEM specs)
Diagnostic algorithm
- Verify code with a scan tool and record freeze-frame data and related codes (look for upstream O2 and catalytic codes).
- Inspect B2S2 connector and wiring for corrosion, damage, poor pins, or disconnection. Repair as needed.
- With ignition off, check continuity from the sensor signal pin to the PCM signal pin; verify no short to chassis ground and correct resistance to PCM (compare to wiring diagram).
- With key on (engine off) backprobe the signal terminal to check reference/idle voltage and ground integrity. Start engine and observe live voltage: downstream should be near mid-range (not stuck low).
- Compare B2S2 to B2S1 (upstream) and to B1 sensors; if upstream oscillates normally and downstream is low, suspect sensor or wiring for B2S2 or catalytic converter issues.
- Check heater circuit: verify heater supply voltage and ground, and measure heater resistance. A failed heater may not set P0157 directly but indicates sensor failure.
- Inspect for exhaust leaks or damage upstream of the sensor; repair leaks then retest.
- If wiring and connectors check good, replace the B2S2 oxygen sensor with OE or quality aftermarket unit.
- Clear codes and perform a drive cycle to confirm the code does not return. If code returns and wiring checked, consider PCM or deeper intermittent wiring harness faults.
Likely causes
- Open or shorted signal wire / poor connector ground between bank 2 sensor 2 and PCM
- Failed O2 sensor (worn or contaminated downstream sensor)
- Corroded connector causing low or intermittent signal
- Exhaust leak between exhaust port and sensor causing erroneous readings
Fault status
Status
O2 Sensor Circuit Low Voltage — Bank 2 Sensor 2. The downstream oxygen sensor signal is reporting an abnormally low voltage; check sensor, wiring/connectors, and exhaust integrity.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
P0157
MITSUBISHI
P — Powertrain
Oxygen sensor2(rear) low
Views:
UK: 12
EN: 22
RU: 27
AI status
Completed
Completed
100%
Causes
- Failed downstream O2 sensor (Bank 2 Sensor 2)
- Damaged, corroded, or disconnected sensor connector or wiring
- Short to ground on the O2 sensor signal circuit
- Exhaust leak upstream of the sensor or damaged exhaust piping
- Contaminated sensor (oil, coolant, silicone, sulfur)
- PCM fault (rare)
Symptoms
- Check Engine MIL illuminated
- Possible failed emissions test
- Usually no obvious drivability problems; sometimes reduced fuel economy
- Possible stored freeze-frame data showing low sensor voltage
What to check
- Scan for P0157 and related freeze-frame/fault history; note conditions when set
- Inspect sensor and connector at bank 2 sensor 2 for corrosion, contamination, or physical damage
- Visually inspect wiring harness for chafing, pinched wires, or melted insulation
- Use scan tool to view live PID for B2S2 voltage and compare to upstream sensor (B2S1) behavior
- Backprobe signal wire with key on (engine off) and with engine running to check voltage
- Check for a short to ground on the signal wire with multimeter (continuity to chassis)
Signal parameters
- Downstream O2 sensor (Sensor 2) expected to be relatively stable near ~0.45 V; not rapidly switching like upstream
- Low-voltage condition commonly defined as sensor signal below ~0.1 V or significantly lower than expected steady voltage
- Upstream (Sensor 1) typically oscillates ~0.1–0.9 V; downstream should be steady near mid-voltage if cat working
- Heater circuit voltage: typically battery voltage (approx. 10–14 V) when key on/run; heater resistance varies by sensor type (check OEM specs)
Diagnostic algorithm
- Verify code with a scan tool and record freeze-frame data and related codes (look for upstream O2 and catalytic codes).
- Inspect B2S2 connector and wiring for corrosion, damage, poor pins, or disconnection. Repair as needed.
- With ignition off, check continuity from the sensor signal pin to the PCM signal pin; verify no short to chassis ground and correct resistance to PCM (compare to wiring diagram).
- With key on (engine off) backprobe the signal terminal to check reference/idle voltage and ground integrity. Start engine and observe live voltage: downstream should be near mid-range (not stuck low).
- Compare B2S2 to B2S1 (upstream) and to B1 sensors; if upstream oscillates normally and downstream is low, suspect sensor or wiring for B2S2 or catalytic converter issues.
- Check heater circuit: verify heater supply voltage and ground, and measure heater resistance. A failed heater may not set P0157 directly but indicates sensor failure.
- Inspect for exhaust leaks or damage upstream of the sensor; repair leaks then retest.
- If wiring and connectors check good, replace the B2S2 oxygen sensor with OE or quality aftermarket unit.
- Clear codes and perform a drive cycle to confirm the code does not return. If code returns and wiring checked, consider PCM or deeper intermittent wiring harness faults.
Likely causes
- Open or shorted signal wire / poor connector ground between bank 2 sensor 2 and PCM
- Failed O2 sensor (worn or contaminated downstream sensor)
- Corroded connector causing low or intermittent signal
- Exhaust leak between exhaust port and sensor causing erroneous readings
Fault status
Status
O2 Sensor Circuit Low Voltage — Bank 2 Sensor 2. The downstream oxygen sensor signal is reporting an abnormally low voltage; check sensor, wiring/connectors, and exhaust integrity.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email