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P0171: System Too Lean Bank 1
Bank 1 is getting too much air or not enough fuel compared with the fuel trim target.
Common causes
- Vacuum leak
- Dirty mass air flow sensor
- Weak fuel pump
- Exhaust leak before oxygen sensor
This free page explains the code. A Shop Brief adapts the next steps to your year, make, model, and full code stack.
Related codes:
P0420P2096P219A Pricing Sample brief