Set Appliance State:
| Isolate Mains Power to appliance as per TOPs P4 |
Remove red wires from CH temperature sensor
Ensure boiler is cool
Ensure boiler is cool
Measurement:
Measure resistance across spade terminals of the sensor.
Resistance should conform approximately to the table below.
Resistance should conform approximately to the table below.

Isolate as per TOPs P4
and refit as necessary