OBD-II code · Powertrain (generic)
P01F5 O2 Sensor Circuit No Activity Detected Bank 1 Sensor 4
Bank 1 sensor 4 O2 sensor shows no signal change despite operating conditions that should produce activity. A drifted or sluggish lambda sensor lets the mixture run lean or rich without correction — fuel economy and emissions suffer immediately.
Is it safe to drive with P01F5?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor dead or unheated
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor B1s4, Sensor Wiring
Related codes
- P01F2O2 Sensor Circuit Low Voltage Bank 1 Sensor 4
- P01F3O2 Sensor Circuit High Voltage Bank 1 Sensor 4
- P01F4O2 Sensor Circuit Slow Response Bank 1 Sensor 4
- P01F6O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 4
- P01F7O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 4
- P01F8Engine Coolant Heater A Control Circuit Driver Current/Temperature Too High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.