OBD-II code · Powertrain (generic, extended)
P2277 O2 Sensor Signal Biased/Stuck Rich (Bank 2 Sensor 3)
O2 sensor at bank 2 sensor 3 reports a rich reading suspiciously stable for too long. Sensor 3 is typically downstream of the second catalyst on systems with three-stage aftertreatment; sensor coated with carbon or fuel residue is the typical cause.
Is it safe to drive with P2277?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor coated
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
- 0.5–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Oxygen Sensor
Related codes
- P2275O2 Sensor Signal Biased/Stuck Rich (Bank 1 Sensor 3)
- P2274O2 Sensor Signal Biased/Stuck Lean (Bank 1 Sensor 3)
- P2276O2 Sensor Signal Biased/Stuck Lean (Bank 2 Sensor 3)
- P2278O2 Sensor Signals Swapped Bank 1 Sensor 3 / Bank 2 Sensor 3
- P2279Intake Air System Leak
- P227ABarometric Pressure Sensor C Circuit
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.