P2271Fuel & Air Metering

O2 Sensor Signal Stuck Rich Bank 1 Sensor 2

P2271 means the downstream O2 sensor on Bank 1 is reporting a stuck-rich signal. The ECM cannot confirm catalyst operation. Usually a failing rear sensor or a genuine rich condition.

🚗 Yes, short-term, but expect an emissions test failure.

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

#1Failing downstream O2 sensor$60-$300

45%

A contaminated or aged sensor sticks rich.

#2Rich running condition$50-$500

25%

Excess fuel keeps the reading rich.

#3Contaminated sensor$60-$300

20%

Oil or coolant contamination skews readings.

#4Wiring/connector fault$50-$250

10%

Corroded connector or heater circuit issue.

🩺 Common Symptoms

Check engine light
Failed emissions test
Slightly worse fuel economy
Possible fuel smell

💰 Repair Cost: DIY vs Shop

DIY Cost

$60-$300

Shop Cost

$150-$500

📋 Free OBD2 Code Cheat Sheet

The 50 most common codes with likely cause and DIY fix cost. Sent once, no spam.

🔧 How to Diagnose P2271

1Read O2 sensor live data for stuck-rich behavior

2Check fuel trims for a rich condition

3Inspect for contamination sources

4Replace the downstream O2 sensor if confirmed

❓ Frequently Asked Questions

Can I drive with P2271?

Short-term yes, but it will fail emissions.

How much to fix P2271?

Usually $150-$500 at a shop; a DIY rear O2 sensor is $60-$300.

What causes P2271 most often?

A failing downstream oxygen sensor or a rich running condition.

🔗 Related Codes

P2270P2272P2273P0136P0141