P01F6O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 4
- 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
- Sensor 4 on bank 1 is a fourth oxygen sensor, downstream of a further converter. No manufacturer or vehicle using sensor 4 codes could be identified (GM and Ford documents stop at sensor 3); the description follows CARB's requirements for downstream sensors and GM's checks on sensor 2. P01F6 means the sensor stays lean: the module deliberately enriches the mixture, and if the sensor does not reach the expected rich voltage before a set amount of air has passed, it counts as stuck lean. GM runs this test on sensor 2 once per trip as a two-trip fault. Usual causes are an aged sensor, an exhaust leak ahead of it or a signal wire shorted to ground.
- What you may notice
- Check engine light on (usually after two drive cycles)
- Catalyst monitor readiness possibly not set
- Usually no change in driving
- Likely causes
- LikelySensor aged, characteristic shifted lean
- PossibleExhaust leak or false air upstream of the sensor
- PossibleSignal wire shorted to ground or contact resistance
- RareMisfires or mixture fault (excess oxygen)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €60 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.