Powertrain
generic / SAE
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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number2 / 71
Possible causes
- Downstream sensor failed stuck rich high
- Downstream sensor contaminated medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 60–500 €
- Estimated time: 0.3–2 h
- Component: oxygen sensor downstream
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012