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.
Exhaust Heat Control Valve: Operation
On cold engine starts, manifold vacuum is directed to exhaust heat control valve through the top two ports of the PVS, closing valve against the spring in vacuum motor. When engine coolant reaches a specified temperature, the PVS shuts off vacuum supply and vents exhaust heat control valve vacuum motor to atmosphere. This allows the spring in the vacuum motor to open the exhaust pipe butterfly valve.
| Body Color | Opening Temp. °F (°C) |
|---|---|
| Black | 92-98 (33-37) |
| Blue | 125-131 (52-55) |
| Purple | 157-163 (69-73) |
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.