Hello Everyone! I am new.

My 2000 Corolla started to have an Engine Check light on with poor economy. Dealer charged $50 to give a code of P0171 (Fuel injection system lean per Haynes manual) -- and recommended "Mass Air Flow Meter to replace". Self checked the MAF sensor (resistance/voltage etc.)but no sign of failure was seen. Disconnecting the battery could clear the light, but will ba back on after some driving.

I wonder why dealer pointed to the MAF sensor(?) while no close codes (for sensors) are given? Possible with other sensors (Oxygen ones)?

Thanks in advance.

* Correction: the code in title should be P0171 (typo).