DTC P1171: Fuel System Lean During Acceleration: Description

PCM can determine if engine is running rich when vehicle operator demands heavy acceleration. When heavy acceleration is demanded, PCM will go into power enrichment mode. During this mode, a lower air/fuel ratio than 14.7:1 (around 12.0:1) will be commanded and fuel injector pulse width will increase. During this condition, PCM should detect HO2S1 signal voltage go high and remain there. DTC sets when PCM is in power enrichment mode and HO2S1 signal voltage is too low.