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)
Disconnect connector at X19
Note that this connector will usually just be a link unless an external sensor has been fitted (e.g. for underfloor heating).
Disconnect connector at X19
Note that this connector will usually just be a link unless an external sensor has been fitted (e.g. for underfloor heating).
Measurement:
Check for continuity (zero resistance) across X19.
