P0172 on a Volvo: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

You can drive short-term, but the rich mixture wastes fuel and can damage the catalytic converter, so get it fixed soon.

What P0172 means on a Volvo

On a Volvo, P0172 means bank 1 is running rich — too much fuel or not enough air in the mixture. The Volvo computer has already trimmed fuel as far as it can and still sees a rich condition, so it sets the code.

Is P0172 common on Volvos?

P0172 appears on Volvos with higher mileage, often on the S60, S80, and XC60. The MAF sensor is a known trouble spot on many Volvo engines and a common cause of rich codes. Aging oxygen sensors and leaking fuel injectors are also frequent causes.

Commonly reported on: S60, S80, XC60, XC90.

Symptoms

Check engine light on
Poor fuel economy
Strong fuel smell from the exhaust
Rough idle

Common causes

most common: Contaminated or failing MAF sensor
common: Aging or faulty oxygen sensor
common: Leaking fuel injector
less common: Faulty fuel pressure regulator holding pressure too high
less common: Restricted air filter or intake

How to fix it

Fix	DIY?	Typical cost
Clean or replace the MAF sensor	Yes	$10–300
Replace the faulty oxygen sensor	Yes	$60–200
Replace leaking fuel injectors or the pressure regulator	Mechanic	$200–600