P0151O2 Sensor Circuit Low Voltage Bank 2 Sensor 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Check engine light on
- Higher consumption, possibly rough running (no mixture control)
- Higher emissions, possible emissions test failure
- Possibly with P0174/P2197
- Likely causes
- LikelySignal wire (or a wide-band sensor wire) shorted to ground, e.g. chafed on exhaust or gearbox
- LikelySensor faulty or poisoned (permanently lean signal)
- PossibleLarge exhaust leak ahead of the sensor or misfires
- PossibleConnector wet or corroded
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €350
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.