Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Disconnect black wires from the thermistor

Measurement:

Measure the resistance across the exposed terminals of the thermistor. Resistance will vary according to the temperature of the water. The lower the temperature the higher the resistance.
The resistance should conform to the table below:
Temperature °CResistance in kOhms
30-509.8-4.7
50-704.7-2.4
70-902.4-1.3
90-1101.3-0.1
Reconnect leads after test.