What does code P0172 mean on a Buick and is it safe to drive?
P0172: System Too Rich (Bank 1). Here's what it means on your Buick, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
PowertrainMedium urgency
What this code means
Too much fuel relative to air. O2 sensor detects low oxygen in exhaust; PCM is reducing fuel trim.
Common causes for your Buick
- Faulty MAF or O2 sensor
- Leaking fuel injector(s)
- High fuel pressure
- Faulty purge valve stuck open
Symptoms
- Check Engine Light
- Rich smell, black smoke
- Poor fuel economy
- Rough idle possible
Typical fixes
- Replace MAF or O2 sensor
- Test fuel pressure and injectors
- Replace purge valve if stuck open
Repair cost range
For a Buick, repairs for P0172 often fall between $100 and $600, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Buick
Buick P0172 rich condition on the 3.6L LFX is often caused by a leaking fuel injector or a stuck-open purge solenoid flooding the intake with EVAP vapor. On 2.0T Ecotec turbo, a leaking boost pressure sensor or a failed MAP sensor can also cause over-fueling.
Most commonly affected models
Enclave 3.6L 2008–2017Regal 2.0T 2011–2017LaCrosse 3.6L 2010–2016