P2271 — O2 Sensor Signal Biased/Stuck Rich (Bank 1 Sensor 2)
Category: Powertrain Severity: Low
Updated:
DTC code P2271 means: O2 Sensor Signal Biased/Stuck Rich (Bank 1 Sensor 2). It falls under the "Powertrain" category, with an estimated severity of Low. Common causes include failed downstream O2 sensor, persistent rich mixture and oil or antifreeze contamination; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Failed downstream O2 sensor
- Persistent rich mixture
- Oil or antifreeze contamination
Symptoms
- Check engine light
- No drivability symptoms
How to diagnose it step by step
- Watch the sensor on deceleration.
- Check fuel trims.
- Replace the sensor.
How to fix it
Decelerate with your foot off the throttle: the sensor should drop below 0.2 V. If it doesn't, replace it.
Estimated repair cost
$100–280.
Frequently asked questions
What does DTC code P2271 mean?
O2 Sensor Signal Biased/Stuck Rich (Bank 1 Sensor 2).
Is code P2271 serious?
Severity Low. Usually a minor fault; check the causes listed.
Can I keep driving with code P2271?
Yes, it is safe to drive.
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