Thermostat: Testing and Inspection

Map Controlled Engine Cooling Thermostat, Checking

Special tools, testers and auxiliary items required

• Hand-Held Multimeter (V.A.G 1526 B)

• Connector Test Set (V.A.G 1594 C)

Test Conditions

• Engine cold

Check internal resistance of heating element

- Separate electrical connection - 2 - at Map Controlled Engine Cooling Thermostat.





- Connect multimeter to thermostat for resistance measurement.

• Specified value: 14 to 16 ohms at 25 °C.

If specification is not obtained:

- Replace thermostat. Refer to => [ Thermostat Housing with Map Controlled Engine Cooling Thermostat ] Thermostat Housing With MAP Controlled Engine Cooling Thermostat.

Thermostat function test

- Remove Map Controlled Engine Cooling Thermostat ( F265). Refer to => [ Thermostat Housing with Map Controlled Engine Cooling Thermostat ] Thermostat Housing With MAP Controlled Engine Cooling Thermostat.

- Check thermostat when it is cold.

• Large valve plate - arrow - must seal all around against connection flange.





If this is not the case:

- Replace thermostat. Refer to => [ Thermostat Housing with Map Controlled Engine Cooling Thermostat ] Thermostat Housing With MAP Controlled Engine Cooling Thermostat.

- Connect thermostat contacts to a battery using the adapter cables from (V.A.G 1594 C).





- Using pliers, carefully place the thermostat into a pot of boiling water at a right angle up to its flange.

• The heating element also warms the wax in the thermostat.

• Do not perform this test in the open air otherwise the expanding material will get damaged.

- Make sure the minimum range of 7 mm - a - is reached after 10 minutes.

If the minimum rage is reached:

- Disconnect voltage supply to battery.

If minimum range is not achieved:

- Replace thermostat. Refer to => [ Thermostat Housing with Map Controlled Engine Cooling Thermostat ] Thermostat Housing With MAP Controlled Engine Cooling Thermostat.

- As a final step, check Engine Control Module (ECM) DTC memory and erase it if necessary, since malfunctions were stored by disconnecting the connectors. Refer to