1 EGR solenoid valve
2 Boost pressure control solenoid valve
NOTE: The EGR solenoid valve and boost control solenoid valve each operate in a closed control loop (see section on “EGR system” or “Boost pressure control” in this brochure).
The solenoid valves are supplied with a vacuum by the vacuum pump.
The signals from the PCM control this vacuum, as a result of which the boost pressure is regulated by means of a vacuum unit and the EGR flow is regulated by the EGR solenoid valve.
The current of these signals determines the vacuum which is sent to the EGR solenoid valve or to the turbocharger vacuum unit.
Effects in the event of a faulty EGR solenoid valve
The EGR system is switched off.
reduced engine power output
increased emissions of black smoke
Effects in the event of a faulty boost pressure
control solenoid valve
reduced engine power output
Diagnosis
The monitoring system checks:
โข the relevant solenoid valve for short circuit and open circuit.