Set Appliance State:
Set Multimeter to Resistance 
Isolate Mains Power to appliance as per TOPs P4
Disconnect yellow wires from DHW sensor
Disconnect yellow wires from DHW sensor
Measurement:
Measure resistance across spade terminals of the sensor.
Resistance should conform to the following table:
Resistance should conform to the following table:
| Temperature °C | Resistance in kOhms |
| 10 | 19.9 |
| 20 | 12.5 |
| 30 | 8.1 |
| 40 | 5.3 |
| 50 | 3.6 |
| 60 | 2.5 | 70 | 1.8 |
| 80 | 1.3 |
Isolate as per TOPs P4
and refit as necessary