Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to Resistance 
Remove connector marked CON2 from PCB 40
Measurement:
Measure resistance across the grey leads at the right of the plug that are connected to the sensor.
The resistance measured will depend upon the temperature of the boiler, the higher the temperature the lower the resistance.
The resistance should conform with the table below.
The resistance measured will depend upon the temperature of the boiler, the higher the temperature the lower the resistance.
The resistance should conform with the table below.
Temperature °C | Resistance in kOhms |
| 20 | 9.0 - 11.0 |
| 60 | 2.0 - 2.5 |
| 85 | 1.0 - 1.5 |
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Isolate as per TOPs P4
and refit as necessary