P2270Fuel & Air Metering

O2 Sensor Signal Stuck Lean Bank 1 Sensor 2

P2270 means the downstream O2 sensor on Bank 1 is reporting a stuck-lean signal, so the ECM cannot verify catalytic converter operation. Usually a failing rear O2 sensor or an exhaust leak.

🚗 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 rear sensor sticks lean.

#2Exhaust leak near the sensor$50-$400

30%

Fresh air intrusion skews the reading lean.

#3Wiring/connector fault$50-$250

15%

Corroded O2 sensor connector or heater circuit issue.

#4Lean running condition$50-$500

10%

A true lean mixture pushes the reading lean.

🩺 Common Symptoms

Check engine light
Failed emissions test
Slightly worse fuel economy
No major drivability change

💰 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 P2270

1Check for exhaust leaks near the rear O2 sensor

2Read O2 sensor live data for stuck-lean behavior

3Inspect the sensor connector and heater circuit

4Replace the downstream O2 sensor if confirmed

❓ Frequently Asked Questions

Can I drive with P2270?

Short-term yes, but it will fail emissions and should be fixed within a few weeks.

How much to fix P2270?

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

What causes P2270 most often?

A failing downstream oxygen sensor, followed by an exhaust leak near the sensor.

🔗 Related Codes

P2271P2272P2273P0136P0141