Set Appliance State:
Use Insulation Mat as required
Set Multimeter to AC Volts 
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Selector switch to Water
Gain access to PCBs
Selector switch to Water
Gain access to PCBs
| WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure |
Measurement:
Allow fan to run and ignition sequence to commence.
Test 1:
Measure the voltage between connection 6 (brown wire) on connector X22 and neutral X4 on main driver board.
Test 2:
Measure the voltage between connection 7 (brown wire) on connector X22 and neutral X4 on main driver board.
Note:
Voltage will only be present at test points during ignition sequence, voltage should cease and boiler will go to lockout after approximately 7 seconds.
Boiler may have to be reset between tests.
Test 1:
Measure the voltage between connection 6 (brown wire) on connector X22 and neutral X4 on main driver board.
Test 2:
Measure the voltage between connection 7 (brown wire) on connector X22 and neutral X4 on main driver board.
Note:
Voltage will only be present at test points during ignition sequence, voltage should cease and boiler will go to lockout after approximately 7 seconds.
Boiler may have to be reset between tests.
Isolate as per TOPs P4
and refit as necessary