P2271 code meaning
O2 Sensor Signal Biased/Stuck Rich (Bank 1, Sensor 2)
Powertrain system Generic code P22xx codes Check engine light
What P2271 means
P2271 is the opposite fault of the same bank 1 rear sensor: its voltage refuses to fall when the exhaust should be lean. It is usually checked during a deceleration fuel cut, when almost pure air passes the sensor. GM's 2018 four-cylinders set it if the signal is still above 100 mV after 25 g of air in fuel cut-off (Type B); GM's Bosch-based 2005 V6 looks for a reading above 0.2 V four seconds into the cut, VW's 2014 data books for CC and Tiguan use 0.15 V after 3000 mg of oxygen, and Ford added a fuel-cut stuck test from model year 2019. Causes are a sensor poisoned by coolant, oil or silicone, a signal wire touching voltage, or a front sensor misleading the ECM; Honda traced this on the 2007 to 2008 Acura TSX and replaced both sensors. P2097 and P0138 cover trim and circuit.
P2271 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P2271
- Malfunction indicator lamp on
- Catalyst monitor not completing
Common causes of P2271
- Most likelyRear oxygen sensor contaminated by coolant, oil or silicone
- PossibleFaulty front A/F sensor making the rear sensor look stuck rich
- Less likelySignal wire chafed against a voltage source
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Oxygen sensor downstreamOxygen sensor upstreamOxygen sensor wiring
What each part of P2271 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 2 | Area: fuel and air metering (injector circuit). |
| 71 | The exact fault in that area. |
What to do next
- Note P2271 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2271
What does P2271 mean?
P2271 means "O2 Sensor Signal Biased/Stuck Rich (Bank 1, Sensor 2)". P2271 is the opposite fault of the same bank 1 rear sensor: its voltage refuses to fall when the exhaust should be lean. It is a generic code, so it means the same on every make.
Is it safe to drive with P2271?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2271 fail an emissions test?
Yes, it can. P2271 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2271 to fix?
Difficulty: medium. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2271 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.