What does code P0172 mean on a Lexus and is it safe to drive?
P0172: System Too Rich (Bank 1). Here's what it means on your Lexus, 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 Lexus
- 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 Lexus, 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 Lexus
Lexus 2GR-FE P0172 rich Bank 1 is uncommon on these reliable engines. When it occurs, a stuck-open EVAP purge valve or a leaking fuel injector is typically responsible. Confirm with live fuel trim data before replacing any parts.
Most commonly affected models
RX350 2GR-FE 2007–2015ES350 2GR-FE 2007–2012