P0131 on a GMC: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

You can keep driving, but fuel economy drops and the catalytic converter can be damaged if the lean condition is left unfixed.

What P0131 means on a GMC

On a GMC, P0131 means the upstream oxygen sensor on bank 1 is sending a low-voltage signal, which the engine computer reads as a lean mixture. On GMC trucks and SUVs, an exhaust leak before the sensor or a vacuum leak is often behind the reading, not the sensor itself.

Is P0131 common on GMCs?

P0131 is seen on GMC models with higher mileage, especially Sierra and Yukon trucks with the V8 engines and Terrain and Acadia crossovers. Exhaust manifold leaks and intake gasket leaks are common causes, and upstream sensors also simply age out after years of service.

Commonly reported on: Sierra, Yukon, Terrain, Acadia.

Symptoms

Check engine light on
Rough idle or hesitation
Poor fuel economy
Slight loss of power

Common causes

most common: Exhaust leak before the upstream sensor
common: Vacuum or intake leak
common: Faulty upstream oxygen sensor
less common: Damaged wiring or connector at the sensor

How to fix it

Fix	DIY?	Typical cost
Fix the vacuum or intake leak	Yes	$20–150
Replace the upstream oxygen sensor	Yes	$80–250
Repair the exhaust leak before the sensor	Mechanic	$200–700
Repair sensor wiring or connector	Mechanic	$100–300

Frequently asked questions

Can I drive a GMC with a P0131 code?

Yes, for short trips. The truck still runs, but fuel economy drops and the catalytic converter can be damaged if the lean condition continues for a long time.

What usually causes P0131 on a GMC?

On GMC trucks an exhaust leak before the sensor is a common cause, and on crossovers a vacuum or intake leak often is. The sensor itself fails less often.

How much does it cost to fix P0131 on a GMC?

A hose or gasket fix can be under $150. Replacing the upstream oxygen sensor typically runs $80–250, and an exhaust manifold leak repair can cost more.