Checking the coolant temperature sensor (VW Passat B4)

Turn off the ignition.

Disconnect the 4-pin connector of the coolant temperature sensor, connect an ohmmeter to terminals "1" and "3" of the sensor (fig. 2-128). measure the temperature of the coolant with a thermometer and check the resistance with an ohmmeter, which should be within the range:

• 3.5-4.5 kOhm at a coolant temperature of 10°C,
• 2.25-3.00 kOhm at 20°C,
• 1.0-1.5 kOhm at 40°C,
• 0.55-0.65 kOhm at 60°C,
• 0.275-0.375 kOhm at 80°C,
• 0.150-0.275 kOhm at 100°C.

Note: Pins "2" and "4" of the sensor are connected to the coolant temperature gauge in the instrument cluster.