Checking the electric fan switch sensor (Audi 80 B3)

The sensor must be checked if the fan does not turn on when the engine is warm. First, check whether the thermostat, radiator, and expansion tank cap of the cooling system are in good condition.

The electric fan switch sensor is located on the bottom right of a 4-cylinder engine, and on the bottom left of a 5-cylinder engine near the radiator. Depending on the version, a 2- or 3-pole sensor can be installed.

Check fuse #5 of the electric fan. Replace if necessary.

Check that the radiator in the area of the thermal switch is hot.

Remove the thermal switch plug, connect the terminals of both wires to the thermal switch with a tested wire.

If the electric fan starts working, the thermal switch should be replaced. With a 2-stage fan, check both stages in this way. First connect + to terminal 1, then to terminal 2.

If the electric fan does not work, or works in one of the two connection options, check the electrical connections. Check the quality of the contacts. If necessary, replace the electric fan.

Sensor tightening torque: 25 Nm.

Check the new sensor. Start and warm up the engine. Let the engine run long enough to check the operation of the electric fan.