Set Appliance State:
Gas Off
| Isolate Mains Power to appliance as per TOPs P4 |
Set Multimeter to DC Volts 
CH Demand
Main On/Off Control in the On position
CH Temperature Control to Maximum
CH Temperature Control to Maximum
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
If a fault code is displayed press boiler 'Reset' button.
Measure DC Voltage across bottom/right hand connection (+ve) on the small 3 pin orange plug to a suitable earth point.
Voltage should be approximately 1V to 3.5V DC.
Measure DC Voltage across bottom/right hand connection (+ve) on the small 3 pin orange plug to a suitable earth point.
Voltage should be approximately 1V to 3.5V DC.
Isolate as per TOPs P4
and refit as necessary