P0171Medium severity

System Too Lean Bank 1

The engine is running too lean on bank 1, meaning too much air or not enough fuel.

Safe to Drive?
Yes

Informational only. Consult a qualified mechanic.

Estimated Repair Cost
$100 - $500
Common Causes
  • Vacuum leak
  • Weak fuel pump
  • Dirty fuel injectors
  • Faulty MAF sensor
  • Exhaust leak before O2 sensor
Recommended Action

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.

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