P01F5O2 Sensor Circuit No Activity Detected 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. P01F5 means that with a warm engine and heated sensor the signal does not switch between rich and lean but stays in the middle or at the bias voltage the module applies. For sensor 2, GM detects this when the signal stays above 1.7 V of a 1.9 V bias, a two-trip fault. Usual causes are an open signal or ground wire or a dead sensor.
- 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
- LikelySignal or ground wire open, connector corroded
- PossibleSensor aged or poisoned, produces no voltage
- PossibleSensor heater faulty, sensor does not reach operating temperature
- RareExhaust leak upstream of the sensor
- 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.