Set Appliance State:
Set Multimeter to Continuity 
Isolate Mains Power to appliance as per TOPs P4
Remove both white wires from High Limit Thermostat
Remove both white wires from High Limit Thermostat
Measurement:
Check the continuity of the High Limit Thermostat (reset table type located on facia).
NOTE:
Ensure that the boiler is cool before carrying out the test.
NOTE:
Ensure that the boiler is cool before carrying out the test.
Isolate as per TOPs P4
and refit as necessary