Dirty or leaking fuel injector; Dirty or faulty mass air flow (MAF) sensor; Faulty fuel pressure regulator or pressure sensor; Faulty or worn oxygen sensor.

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P0172: System too rich (Bank 1)

Q: What does P0172 mean?

System too rich (Bank 1): The engine is getting too much fuel or too little air on bank 1. The computer cannot correct it with its normal adjustments.

Q: Can I drive with P0172?

Fix soon. Usually drivable for a short time, but get it checked soon. Ignoring it can waste fuel, raise emissions and lead to more damage.

Fix soonSystem: Fuel and air

What P0172 means

The engine is getting too much fuel or too little air on bank 1. The computer cannot correct it with its normal adjustments.

Common symptoms

Worse fuel economy
Black smoke or sooty exhaust
Rough or unstable idle
Smell of fuel

Common causes

Dirty or leaking fuel injector
Dirty or faulty mass air flow (MAF) sensor
Faulty fuel pressure regulator or pressure sensor
Faulty or worn oxygen sensor

Can I keep driving?

Fix soon. Usually drivable for a short time, but get it checked soon. Ignoring it can waste fuel, raise emissions and lead to more damage.

What to do next

Write down the code and any symptoms you notice.
Check the simple things first: the fuel cap, loose connectors and fluid levels where they apply.
Do not just clear the code. If the light comes back, the cause is still there and needs a proper diagnosis.
Read live data and freeze frame data with an OBD-II scanner app to see what the car was doing when the code was set.

Read P0172 from your own car

DriveHub connects to a $15 to $30 OBD-II adapter, reads the code from your car and explains it in plain English. iPhone and Android.

App Store Google Play Try the free code decoder

General information, not a diagnosis. Causes vary by make, model and engine. If you are unsure, have the car inspected.