2020 GMC P0172: What It Means & Is It Safe to Drive?
P0172 on the 2020 GMC: System Too Rich (Bank 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe 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 on the 2020 GMC
- 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 2020 GMC, repairs for P0172 typically fall between $100 and $600, depending on the root cause and labor rates in your area.
Known issues on GMC
GMC P0172 rich Bank 1 on the 5.3L V8 is typically a leaking fuel injector or stuck purge valve. On the 3.6L LLT V6 Acadia, a rich condition alongside rough idle often points to a stuck EVAP purge solenoid admitting excess vapor—inspect the purge valve first.
Most commonly affected models
Sierra 5.3L 2007–2014Acadia 3.6L 2007–2016Terrain 2.4L 2010–2017