P0151 code meaning
O2 Sensor Circuit Low Voltage Bank 2 Sensor 1
Powertrain system Generic code P01xx codes Check engine light
What P0151 means
The oxygen sensor before the catalytic converter on bank 2 (sensor 1) is the main control sensor for the mixture. It is either a switching sensor (about 0.1 V lean to 0.9 V rich) or a wide-band sensor that works with a pump current evaluated by an interface chip. Bank 2 exists only on engines with two exhaust manifolds. P0151 is the bank 2 counterpart of P0131. On switching sensors the signal stays below about 40–50 mV in closed loop with a stoichiometric target (GM LT4: 285 of 350 samples; GM 3.0/3.6 V6 within 50 s); on wide-band sensors the interface chip reports a sensor wire shorted to ground. Two trips. A genuinely lean bank 2 shows up as P0174 rather than this code. A stored code usually switches mixture control to open loop and suspends adaptation and converter monitoring.
P0151 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0151
- Check engine light on
- Higher consumption, possibly rough running (no mixture control)
- Higher emissions, possible emissions test failure
- Possibly with P0174/P2197
Common causes of P0151
- Most likelySignal wire (or a wide-band sensor wire) shorted to ground, e.g. chafed on exhaust or gearbox
- Most likelySensor faulty or poisoned (permanently lean signal)
- PossibleLarge exhaust leak ahead of the sensor or misfires
- PossibleConnector wet or corroded
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor bank2 sensor1Oxygen sensor wiringEngine control module
What each part of P0151 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 51 | The exact fault in that area. |
What to do next
- Note P0151 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0151
What does P0151 mean?
P0151 means "O2 Sensor Circuit Low Voltage Bank 2 Sensor 1". The oxygen sensor before the catalytic converter on bank 2 (sensor 1) is the main control sensor for the mixture. It is a generic code, so it means the same on every make.
Is it safe to drive with P0151?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0151 fail an emissions test?
Yes, it can. P0151 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0151 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0151 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.