P2271: Oxygen sensor signal biased or stuck rich (bank 1, sensor 2)
The bank 1 oxygen sensor after the catalyst reads rich and does not move. Usually the sensor, its wiring or genuinely too much fuel.
| Code | P2271 |
|---|---|
| System | Engine and transmission |
| Group | P22xx, NOx sensors, oxygen sensors and emissions |
| Type | Generic: it means the same on every make |
| Can you keep driving? | Yes, no rush |
What P2271 means
The sensor after the catalytic converter (sensor 2) checks that the catalyst is working. Here the bank 1 sensor keeps reading rich (little oxygen) even when it should not, for example when you lift off the throttle. Bank 1 is the side of the engine with cylinder 1.
Most common causes
- Contaminated or faulty downstream oxygen sensor
- Sensor signal wire touching a voltage source
- Moisture or corrosion in the connector
- Engine genuinely running rich (leaking injector, purge valve)
- Engine burning oil or coolant and fouling the sensor
Symptoms
- Engine warning light on
- Engine usually runs as normal
- Possible inspection failure because of the warning light
Can you drive with P2271?
Yes, no rush You can drive as normal; this sensor does not control the engine. If there are also rich mixture codes or a fuel smell, get that checked first to protect the catalyst.
Open the bonnetthe in-depth explanation
How to check it
Watch bank 1 sensor 2 live when you lift off the throttle while moving: on overrun the injection cuts and the voltage should drop to about 0.1 volts. If it stays high, the sensor or its wiring is the suspect.
How to read and clear P2271 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P2271 with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P226B The boost pressure of the turbocharger or supercharger is too high
- P226C The turbocharger boost control A responds slowly
- P226F The turbocharger boost control B responds slowly
- P2270 Oxygen sensor signal biased or stuck lean (bank 1, sensor 2)
- P2272 Oxygen sensor signal biased or stuck lean (bank 2, sensor 2)
- P2273 Oxygen sensor signal biased or stuck rich (bank 2, sensor 2)
- P2274 The signal from heated lambda sensor 3 on bank 1 stays at lean mixture
- P2275 The signal from heated lambda sensor 3 on bank 1 stays at rich mixture
- P2200 NOx sensor circuit fault (bank 1)
- P2201 NOx sensor circuit range or performance problem (bank 1)
- P2227 Barometric pressure sensor A range or performance problem
- P2228 Barometric pressure sensor A circuit low
What does code P2271 mean?
The sensor after the catalytic converter (sensor 2) checks that the catalyst is working. Here the bank 1 sensor keeps reading rich (little oxygen) even when it should not, for example when you lift off the throttle. Bank 1 is the side of the engine with cylinder 1.
Can you drive with P2271?
You can drive as normal; this sensor does not control the engine. If there are also rich mixture codes or a fuel smell, get that checked first to protect the catalyst.
How do you clear P2271?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P2271 comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
