the engine computer (PCM) turns the "Check Engine" light (MIL) ON and sets the trouble code P0171 - System Too Lean for Bank 1 and (or) P0174 - System Too Lean Bank 2, depending on which cylinder bank is affected. The PCM also stores the ...
Code P0171 relates to the first bank of an engine. The code indicates that the air-to-fuel ratio is running too lean — something that can happen for various reasons. To see the P0171 code, you’ll need a diagnostic scanner. Otherwise, you’ll see a check engine light illuminating the...