Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1993 Volvo 850 AutomaticFACTORY OEM SERVICE PROCEDURE
Testing - EGR Valve Function Test
- 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.
- 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.
- 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.
- If EGR valve still will not open or will not close after opening, clean or replace EGR valve.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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