Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance
as per TOP's P4

Remove the plug connector from the primary thermistor

Measurement:

Measure the resistance across the exposed terminals of the primary thermistor.
The resistance measured will depend upon the temperature of the appliance and should conform to the table below.
Temperature °CResistance in kOhms
20-3012.0-7.5
30-407.5-5.1
40-505.1-3.9
50-603.9-2.9
60-702.9-2.0
70-802.0-1.6
Reconnect plug connector after tests.