How to Replace Coolant Temperature Sensor 99-02 Volvo V70

Difficulty: Intermediate · About 3 min · Volvo V70

Replace the engine coolant temperature sensor on a 1999–2002 Volvo V70 with the engine cold, preserving the thermostat housing seal and refilling the cooling system with specified coolant.

Steps

1. Drain coolant with the engine cold

   Let the engine cool completely before opening the expansion tank. Place a drain pan below the system, drain enough coolant to lower the level beneath the sensor, and close the drain securely.

2. Access the sensor

   Remove the engine cover and move the thermostat housing aside as needed. Keep its sealing surfaces clean and avoid pulling on nearby wiring or hoses.

3. Replace the temperature sensor

   Unclip the sensor harness and remove the sensor with a suitable wrench. Fit the replacement with its correct seal, tighten it to specification, and reconnect the plug and harness retainer.

4. Reinstall housing and refill

   Reinstall the thermostat and housing with sound seals, then refit the engine cover. Refill with the specified coolant and bleed the system using the vehicle's procedure.

5. Check for leaks and confirm level

   Start the engine and monitor temperature while checking the sensor and drain area for leaks. After the engine cools, recheck the coolant level and confirm the temperature reading is plausible.

Check your vehicle’s repair manual for exact specifications and fit.