General Information

Engine Control
P0172 System too Rich (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 P0172 when lambda controller is lower than -30%.

DTC Detecting Condition





Signal Waveform & Data




Fig 1) ENGINE IDLE