P2277: O2 Sensor Signal Biased/Stuck Rich (Bank 2 Sensor 3)
Standardized SAE J2012 code · P22xx — Fuel & air metering and auxiliary emission controls
What does P2277 mean?
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.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Common causes
- High Sensor coated
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P2277 on the same make and model first.
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