What does code P0172 mean on a Toyota and is it safe to drive?
P0172: System Too Rich (Bank 1). Here's what it means on your Toyota, 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 Toyota
- 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 Toyota, 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 Toyota
P0172 on Toyota 2AZ-FE and 1MZ-FE engines often results from a stuck-open fuel injector or a faulty upstream O2 sensor. A coolant temperature sensor reading too cold can also cause over-fueling on cold starts.
Most commonly affected models
Camry 2002–2011RAV4 2006–2012Sienna 2004–2010