Called to one of these today. Not seen one for ages (should all have been ripped out by now). Fault is that the boiler is not working. With the boiler turned on, no ignition sequence. There is a live to the PCB but no sparking at the spark probe. If you disconnect the 5 wire multiblock from the plug above the PCB then it starts sparking at the electrode, but no gas to ignite due to the plug being disconnected. If you reconnect the plug it immediately stops sparking again. I suspect the PCB but this is a rather costly suspicion as they are not returnable. Any ideas or confirmation please. 
