Thermal Vacuum Valve: Testing and Inspection

Fig. 5 EGR Thermo Valve:

1. Start engine and run at idle until it reaches normal operating temperature.
2. Disconnect vacuum hose from EGR valve.
3. Apply intake manifold vacuum to EGR valve.
4. If engine does not run rough or stall, test EGR valve.
5. If EGR valve is not defective, replace EGR thermo valve Fig. 5.