Checking the temperature sensor K-Jetronic, KE-Motronic (VW Passat B3)

The temperature sensor is located on the left side of the cylinder head and measures the coolant temperature. A faulty temperature sensor causes problems when starting a cold engine and difficulties when idling. With the KE-Motronic system, if the temperature sensor fails, the control unit switches to a time program. In this case, the following temperature values are accepted as an alternative to the actual values: 0°C when starting the engine and +60°C for all other engine operating ranges. The fault code memory records the presence of a fault.

When installed, the temperature sensor can be tested at different engine temperatures.



green-red wire (K-Jetronic) or, respectively, a plug with a purple-black and brown-white wire (KE-Motronic) and using an ohmmeter measure the resistance between the contact and the body.

K-Jetronic

The resistance values measured at different temperatures are compared with the values shown in the diagram. To do this, the engine is warmed up and the measurements are repeated at different temperatures. In this case, the temperature shown by the coolant temperature gauge is taken as the engine temperature.



KE-Motronic: The diagram above only applies to engines with the K-Jetronic system. The prescribed resistance values at certain temperatures for an engine with the KE-Motronic system are:

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If the measured values do not match the specified values, unscrew the temperature sensor and replace it.