OBD-II code · Powertrain (generic, extended)
P2271 O2 Sensor Signal Stuck Rich (Bank 1, Sensor 2)
The downstream oxygen sensor on bank 1 reports a constant rich signal during a forced-lean command. Suggests a failed downstream sensor or a sensor contaminated by oil/coolant from upstream engine wear.
Is it safe to drive with P2271?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyDownstream sensor failed stuck rich
- PossibleDownstream sensor contaminated
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
- 0.3–2 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor Downstream
Related codes
- P2196O2 Sensor Signal Stuck Rich (Bank 1, Sensor 1)
- P2198O2 Sensor Signal Stuck Rich (Bank 2, Sensor 1)
- P2270O2 Sensor Signal Stuck Lean (Bank 1, Sensor 2)
- P2273O2 Sensor Signal Stuck Rich (Bank 2, Sensor 2)
- P226EParticulate Filter Deteriorated/Missing Substrate (Bank 2)
- P226FTurbocharger Boost Control B Slow Response
- P2272O2 Sensor Signal Stuck Lean (Bank 2, Sensor 2)
- P2274O2 Sensor Signal Biased/Stuck Lean (Bank 1 Sensor 3)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.