What usually causes it
- A vacuum leak, like a cracked or loose rubber hose
- A dirty air flow sensor (MAF)
- A weak fuel pump or a clogged fuel filter
- Dirty or clogged fuel injectors
- An exhaust leak before the front oxygen sensor
P0171Starts at: OK to drive, fix when convenient
Engine is running lean (bank 1)
The engine is getting too much air or not enough fuel on bank 1, the side with cylinder 1. The computer is adding extra fuel to make up for it and has hit its limit.
Check this first
Make sure the oil filler cap and the dipstick are fully seated. Then listen for a hissing sound near the engine and look for cracked rubber hoses.
What to watch for
- Rough idle, or stumbling when you press the gas
- A flashing check engine light, which means a bad misfire
- Poor gas mileage
Can I keep driving?
We rate P0171 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 P0171
What does P0171 mean?
Engine is running lean (bank 1). The engine is getting too much air or not enough fuel on bank 1, the side with cylinder 1. The computer is adding extra fuel to make up for it and has hit its limit.
Can I keep driving with P0171?
We rate P0171 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 P0171?
The most common causes, in order: A vacuum leak, like a cracked or loose rubber hose; A dirty air flow sensor (MAF); A weak fuel pump or a clogged fuel filter; Dirty or clogged fuel injectors; An exhaust leak before the front oxygen sensor.
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.