Set Appliance State:
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Remove the plug connector from the DHW thermistor
Remove the plug connector from the DHW thermistor
Measurement:
Measure the resistance across the exposed terminals of the DHW thermistor.
The resistance measured will depend upon the temperature of the appliance and should conform to the table below.
The resistance measured will depend upon the temperature of the appliance and should conform to the table below.
| Temperature °C | Resistance in kOhms |
| 20-30 | 12.0-7.5 |
| 30-40 | 7.5-5.1 |
| 40-50 | 5.1-3.9 |
| 50-60 | 3.9-2.9 |
| 60-70 | 2.9-2.0 |
| 70-80 | 2.0-1.6 |
Isolate as per TOPs P4
and refit as necessary