General Information

Engine Control
P0171 System too Lean (Bank 1) - General Information

Component Location





General Description

PCM controls fuel ratio for exhaust gas control and improvement of fuel efficiency by measuring O2 sensor signal.
Controlling of fuel ratio is divided into short and long time correction, and ideal fuel correction value is 0%.
If the upstream O2 sensor catch that exhaust gas is lean, PCU increases fuel injection and vise versa.

DTC Description

ECU sends P0171 when lambda controller is higher than 50%.

DTC Detecting Condition





Signal Waveform & Data




Fig 1) ENGINE IDLE