Cadillac 12578038 Valve,EGR

To test the EGR solenoid valve on vehicles under 8500 GVW, the ignition should be off, and vacuum applied. If it doesn't hold vacuum, replacement is required. For vehicles over 8500 GVW, the ignition should be on (engine not running) during the test. If the EGR valve moves, disconnecting the electrical connector and repeating the test is necessary. If the EGR valve moves, the solenoid valve should be replaced.

The most common cause of problems in the EGR system is a stuck or corroded EGR valve.

When emitted from the tailpipe, NOx combines with reactive organic compounds and sunlight to form ozone and photochemical smog.

To test the EGR solenoid valve on vehicles under 8500 GVW, the ignition should be off, and vacuum applied. If it doesn't hold vacuum, replacement is required. For vehicles over 8500 GVW, the ignition should be on (engine not running) during the test. If the EGR valve moves, disconnecting the electrical connector and repeating the test is necessary. If the EGR valve moves, the solenoid valve should be replaced.

1996 and later models use an electronically operated EGR valve. You must have these units checked by a dealer service department or other shop with the proper type scan tool that can operate the EGR valve electronically for testing. The EGR valve is usually located on the intake manifold, adjacent to the TBI unit. Most of the time when a problem develops in this emissions system, it's due to a stuck or corroded EGR valve. With the engine cold to prevent burns, push on the EGR valve diaphragm. Using moderate pressure, you should be able to press the diaphragm in-and-out within the housing. The EGA valve diaphragm should move easily with finger pressure. If the diaphragm doesn't move or moves only with much effort, replace the EGR valve with a new one. If in doubt about the condition of the valve, compare the free movement of your EGR valve with a new valve. Some vehicles are equipped with an electronic Vacuum Regulator Valve (VRV). The filter in this valve should be cleaned at regular intervals. The valve is located on a bracket near the EGR valve. Locate the valve and remove the old filter. Clean the filter with a soapy solution and reinstall it. For more information on the EGR system, look for more information.