Circuit Description

Exhaust Gas Recirculation (EGR) system recirculates exhaust gas into intake system to reduce NOx emissions. Amount of EGR is regulated by EGR pressure transducer valve according to engine load. DTC P0401 will set when EGR system is on, and:

Engine is NOT at normal operating temperature.
During deceleration (throttle valve closed).
Light engine load.
Engine speed is over 4400 RPM.

NOTE: If DTCs P0401 and P0402 are both set, diagnose DTC P0402 first.