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 X4 from PCB
Remove connector X4 from PCB
Measurement:
Measure the resistance of the DHW sensor and harness across the two green wires on connector X4.
The resistance depends on temperature and should conform to the table below:
The resistance depends on temperature and should conform to the table below:
| Temperature °C | Resistance in kOhms |
| 20 - 30 | 12.0 - 8.2 |
| 30 - 40 | 8.5 - 5.5 |
| 40 - 50 | 5.8- 3.8 |
| 50 - 60 | 4.0 - 2.7 |
| 60 - 70 | 2.9 - 2.0 |
| 70 - 80 | 2.1 - 1.4 |
Isolate as per TOPs P4
and refit as necessary