What usually causes it
- A dirty air filter or a dirty air flow sensor (MAF)
- A leaking or stuck open fuel injector
- A failing oxygen sensor
- Fuel pressure that is too high
- A coolant temperature sensor that reads wrong
P0172Starts at: OK to drive, fix when convenient
Engine is running rich (bank 1)
The engine is getting too much fuel or not enough air on bank 1, the side with cylinder 1. The computer is cutting back fuel to make up for it and has hit its limit.
Check this first
Look at the air filter. A clogged filter is cheap to replace and can cause this code.
What to watch for
- A strong smell of gas or black smoke from the tailpipe
- A rotten egg smell from the exhaust
- Rough idle or a flashing check engine light, which means a bad misfire
Can I keep driving?
We rate P0172 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
Quick answers about P0172
What does P0172 mean?
Engine is running rich (bank 1). The engine is getting too much fuel or not enough air on bank 1, the side with cylinder 1. The computer is cutting back fuel to make up for it and has hit its limit.
Can I keep driving with P0172?
We rate P0172 as OK to drive, fix when convenient, as a starting point. Keep an eye on the signs below. If the light starts flashing, stop driving soon.
What usually causes P0172?
The most common causes, in order: A dirty air filter or a dirty air flow sensor (MAF); A leaking or stuck open fuel injector; A failing oxygen sensor; Fuel pressure that is too high; A coolant temperature sensor that reads wrong.
Estimates only. A mechanic should confirm. The same code can mean slightly different things on different cars; the app explains it for your exact year, make, model and mileage.