P0151: Oxygen sensor (bank 2, sensor 1): voltage too low
The bank 2 oxygen sensor before the catalytic converter reads a voltage that is too low. Often a damaged wire, the connector or a worn sensor.
| Code | P0151 |
|---|---|
| System | Engine and transmission |
| Group | P01xx, Air and fuel metering |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0151 means
The oxygen sensor before the catalytic converter measures how much oxygen is left in the exhaust, and the ECU uses that to fine-tune the air and fuel mixture. This code means the ECU sees a voltage below what the sensor should produce, nearly always due to a wiring problem or a worn-out sensor. Bank 2 is the side of the engine opposite cylinder 1, and it only exists on V-shaped or boxer engines.
Most common causes
- Sensor connector loose or corroded
- Signal wire with worn insulation touching earth
- Exhaust leak ahead of the sensor letting air in
- Intake air leak making the mixture lean
- Worn-out or faulty oxygen sensor
Symptoms
- Engine warning light on
- Higher fuel consumption than usual
- Slightly rough idle or small hesitations
- High emissions that can fail the inspection
Can you drive with P0151?
With care You can drive, but the mixture may not be controlled properly: fuel use goes up and, left too long, it can end up damaging the catalytic converter. Get it looked at soon.
Open the bonnetthe in-depth explanation
How to check it
With the engine warm and idling, watch this sensor’s voltage in live data: a conventional sensor swings quickly between roughly 0.1 and 0.9 V. If it stays fixed, the problem is the sensor or its wiring (some cars use a wideband sensor, which shows different values).
How to read and clear P0151 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0151 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P014D Heated lambda sensor 1 on bank 1 responds slowly when switching from lean to
- P014E Heated lambda sensor 1 on bank 2 responds slowly when switching from rich to
- P014F Heated lambda sensor 1 on bank 2 responds slowly when switching from lean to
- P0150 Oxygen sensor (bank 2, sensor 1): circuit fault
- P0152 The lambda sensor (bank 2, sensor 1) gives a higher signal than normal
- P0153 Oxygen sensor (bank 2, sensor 1): slow response
- P0154 Heated lambda sensor 1 on bank 2 shows no activity
- P0155 Oxygen sensor heater (bank 2, sensor 1): circuit fault
- P0100 Mass or volume air flow sensor circuit fault
- P0101 Air flow sensor range or performance problem
- P0102 Air flow sensor circuit low input
- P0103 Air flow sensor circuit high input
What does code P0151 mean?
The oxygen sensor before the catalytic converter measures how much oxygen is left in the exhaust, and the ECU uses that to fine-tune the air and fuel mixture. This code means the ECU sees a voltage below what the sensor should produce, nearly always due to a wiring problem or a worn-out sensor. Bank 2 is the side of the engine opposite cylinder 1, and it only exists on V-shaped or boxer engines.
Can you drive with P0151?
You can drive, but the mixture may not be controlled properly: fuel use goes up and, left too long, it can end up damaging the catalytic converter. Get it looked at soon.
How do you clear P0151?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0151 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
