The P0171 diagnostic trouble code indicates that the engine control module (ECM) has detected a lean air-fuel mixture on Bank 1 of the engine.
In simple terms, this means the engine is receiving too much air and not enough fuel.
When P0171 appears, your Check Engine Light will turn on, and the vehicle may begin to run rough, hesitate during acceleration, or consume more fuel than usual.
This is one of the most common OBD2 codes on gasoline engines worldwide.

