EngineLightCodes
Powertrain code

P2271 O2 Sensor Signal Stuck Rich (Bank 1, Sensor 2)

Severity
Fix soon
Typical repair cost
$70–$550
Do it yourself
Possible, medium
Shop time
0.3–2.0 hours

The downstream oxygen sensor on bank 1 reports a constant rich signal during a forced-lean command.

How the engine computer detects it

Suggests a failed downstream sensor or a sensor contaminated by oil/coolant from upstream engine wear.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Check engine light on
  • Increased fuel consumption
  • Possible rough idle or hesitation
  • Failed emissions test

Common causes

  1. Downstream sensor failed stuck rich Most likely
  2. Downstream sensor contaminated Possible

How to diagnose P2271

  1. Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
  2. Inspect the parts involved: oxygen sensor downstream.
  3. Work through the causes above from most to least likely, cheapest checks first.
  4. Clear the code and drive a full drive cycle to confirm the repair held.

Reading the code

P
Powertrain
2
Generic (SAE) code
271
Specific fault

Questions drivers ask

Can I drive with code P2271?

Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.

Will my car pass an emissions inspection with P2271?

Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.

Will P2271 clear by itself?

The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.

Can I fix P2271 myself?

Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.