EGR Control Solenoid: Description and Operation

The EGR Control Solenoid Valve is a computer controlled vacuum switching valve. The Control Unit will internally ground the EGR Solenoid Valve circuit after the engine coolant has reached operating temperature and the engine is at a steady cruise. Until that point the EGR Solenoid is open (circuit ungrounded), and port vacuum is vented back into the air induction system. This valve serves to reduce NOx emissions from the exhaust.

Some vehicles utilize a coolant temperature sensitive Thermo Valve, which is not computer controlled. Refer to EMISSION CONTROLS, for additional testing of the Emission Control Systems and Components.