Function
The EGR valve solenoid valve is actuated via PWM signals from the PCM, in accordance with the required exhaust gas quantity to be recirculated. The duty cycle with which the EGR valve solenoid valve is actuated by the PCM therefore determines the appropriate vacuum level for actuation of the EGR valve and consequently of the EGR quantity.
Effects of faults
In case of a fault, the EGR system is switched off.
Note: If the EGR valve is sticking in the open position, incomplete combustion occurs at high engine speeds due to a lack of oxygen. This results in increased black smoke formation and rough running.
Diagnosis
Exhaust gas recirculation via the EGR valve solenoid valve operates in conjunction with the MAF sensor, in a closed loop control circuit. The EGR valve solenoid valve is monitored for short circuit and open circuit by the output stage in the PCM (via the power consumption of the solenoid valve).
Possible diagnostic trouble codes: P0403, P0405, P0406