P0171
Get Serviced SoonFix: High — schedule within a weekSystem Too Lean (Bank 1) — The engine is receiving too much air or too little fuel on bank 1. Fuel trim has hit its limit trying to add fuel.
Dashboard light triggered
Check Engine LightWhat to do
Check for vacuum leaks, dirty MAF sensor, or weak fuel pump. Get a diagnostic scan to confirm. Safe to drive short distances but schedule service soon.
Common causes
- Vacuum leak (hoses, intake manifold gasket)
- Dirty or faulty mass airflow (MAF) sensor
- Weak fuel pump or clogged fuel filter
- Faulty oxygen (O2) sensor
- Leaking intake manifold
Estimated repair cost
$100–$600
Exact cost depends on the cause, your vehicle, and labor rates in your area.
What to tell your mechanic
Use this script so you sound informed and get a clear diagnosis before agreeing to repairs:
“The check engine light is on with code P0171, system too lean on bank 1. Can you check for vacuum leaks, test the MAF sensor, and inspect the fuel delivery system? I'd like to know the root cause before we replace parts.”
About the Check Engine Light
Code P0171 triggers the Check Engine Light. Indicates an issue with the engine or emissions system. Could range from a loose gas cap to a serious engine misfire.
Read full Check Engine Light guideFrequently asked questions
- What does OBD code P0171 mean?
- System Too Lean (Bank 1) — The engine is receiving too much air or too little fuel on bank 1. Fuel trim has hit its limit trying to add fuel.
- What dashboard light does P0171 trigger?
- P0171 triggers the Check Engine Light.
- How serious is P0171?
- Severity: yellow. Fix priority: High — schedule within a week.
- How much does it cost to fix P0171?
- Repair costs typically range from $100–$600. The exact cost depends on the root cause and your vehicle.
Related OBD codes (same dashboard light)
These codes also trigger the Check Engine Light: