Volvo 850 EGR service manual
P – EGR FUNCTION TESTING
1995 Volvo 850
1989-95 ENGINE PERFORMANCE Volvo EGR Function Testing
1) Ensure all connections are tight and does not leak, vacuum hoses connected and not kinked. Check EGR function with cold and hot engine at different engine RPM.
2) With coolant temperature at less than 131 F (55 C), EGR valve should be closed at all engine speeds. If EGR valve is open, replace thermostatic vacuum switch.
3) With coolant temperature at greater than 140 F (60 C), EGR valve should only open at partial throttle. If EGR valve remains closed, check thermostatic vacuum switch by disconnecting vacuum hose from EGR valve and blowing air into it. Air should flow freely through thermostatic vacuum switch, if not replace thermostatic vacuum switch.
4) If EGR valve still will not open or will not close after opening, clean or replace EGR valve.