What does code P0172 mean and is it safe to drive?
P0172: System Too Rich (Bank 1). Here’s what it means, what usually causes it, what repairs typically cost, and how urgent it is to keep driving.
PowertrainGenerally safe to drive
Repair cost
$100–$600
System
Powertrain
Urgency
medium
What this code means
Too much fuel relative to air. O2 sensor detects low oxygen in exhaust; PCM is reducing fuel trim.
Common causes
- 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
Repairs for P0172 often fall between $100 and $600, depending on the cause and your vehicle.