Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Gain access to PCB (use Insulation Mat as required)
Remove connector X5 from the PCB
Remove connector X5 from the PCB
Measurement:
Measure the resistance across connection 3 (purple) and 4 (purple) at connector X5. The resistance will depend upon the temperature of the water the hotter the water the lower the resistance.
The resistance should conform to the table below.
Ensure that test is carried out at disconnected connector X5
Reconnect connector after test.
The resistance should conform to the table below.
| Temperature °C | Resistance in kOhms |
| 20-25 | 12.5-11.0 |
| 25-30 | 11.0-10.0 |
| 30-35 | 10.0-5.5 |
| 35-40 | 5.5-4.0 |
Ensure that test is carried out at disconnected connector X5
Reconnect connector after test.
Isolate as per TOPs P4
and refit as necessary