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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 at a glance
CodeP2271
SystemEngine and transmission
GroupP22xx, NOx sensors, oxygen sensors and emissions
TypeGeneric: 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.

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 this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

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 the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P2271 is a generic code, so it means the same on any make, for example on Abarth, Citroën, Cupra, Hyundai, Mini, Seat. See what Final OBD does on your car in makes and models.

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.