What does code P0172 mean on a Infiniti and is it safe to drive?
P0172: System Too Rich (Bank 1). Here's what it means on your Infiniti, 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 Infiniti
- 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 Infiniti, 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 Infiniti
Infiniti VQ bank 1 rich condition. A leaking fuel pressure regulator is the most common cause on G35 and G37. A faulty MAF sensor reading low (causing the ECU to over-fuel) is the secondary cause; compare MAF readings to spec before replacing the regulator.
Most commonly affected models
G35 2003–2007G37 2008–2013FX35 2003–2008