System Too Lean Bank 1
The engine is running too lean on bank 1, meaning too much air or not enough fuel.
Informational only. Consult a qualified mechanic.
- Vacuum leak
- Weak fuel pump
- Dirty fuel injectors
- Faulty MAF sensor
- Exhaust leak before O2 sensor
Check for vacuum leaks, clean MAF sensor, and inspect fuel system.
What does P0171 mean?
The P0171 OBD-II diagnostic trouble code (DTC) indicates: system too lean bank 1. This is a medium-severity powertrain code that your vehicle's onboard diagnostics system triggers when the engine is running too lean on bank 1, meaning too much air or not enough fuel. If your check engine light is on with this code, the vehicle is generally safe to drive, but you should have it inspected soon.
Use Your Service Book to log this diagnostic trouble code to your vehicle's service history, track repairs, and get maintenance reminders — all for free.
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