Set Appliance State:
Mains Power Off
Set Multimeter to DC Volts 
Turn Hot Water Tap On
Preheat switched OFF
| WARNING! - Mains voltage is expected during test follow TOPs P4 live testing procedure |
Measurement:
Reset boiler if required.
Allow appliance to go through it's ignition sequence.
Measure for DC voltage across the BLUE and BLACK wires of the gas valve connector.
Voltage will only be present for approximately 3 seconds once sparking is heard.
Expected voltage approximately 210 - 230 Vdc.
Note.
The appliance will try to ignite 5 times before going to lockout, reset as required until test is complete.
Allow appliance to go through it's ignition sequence.
Measure for DC voltage across the BLUE and BLACK wires of the gas valve connector.
Voltage will only be present for approximately 3 seconds once sparking is heard.
Expected voltage approximately 210 - 230 Vdc.
Note.
The appliance will try to ignite 5 times before going to lockout, reset as required until test is complete.
Isolate as per TOPs P4
and refit as necessary