One morning my boiler stopped delivering hot water. I went to have a look and on the control panel the "flame failure" LED was flashing. I have tried rotating the control nob to the Reset position and then the boiler attempts to restart. It makes a few clicks and the sound of the fan starting but fails. It does this about 6 times and then stops. For some reason its just failing to restart.

I have tried doing this reset several times now and also turned it off from the mains and back on again. Each time the result is the same. However on a couple of tries, the "Air flow monitor" LED flashes in addition to the "flame failure" LED. DOes this indicate a blockage? I would be tempted to see if the flues are blocked but I dont know if its safe to take off either of the 2 flues at the top of the boiler!!

Anyone have any ideas?

midvale99, November 2009

I had exactly this problem on my Baxi 105e. The fan would run and it would have a few abortive tries and then it would give up and start flashing the flame failure LED (sometimes with or without the fan failure LED). I changed the pressure switch (£24) and the fan (£102), to no avail. My third attempt was to change the PCB (£122), and it has fixed the problem.

Looking back, I wish I had trusted my instincts....... Originally I tested the pressure switch was actually switching the power using a 240v test screwdriver and it indicated that it was working OK. I needlessly changed the switch and fan because of the fan LED flashing. Then, when I removed the PCB, there was an obvious burn mark around one of the terminals on the back, indicating this was definately the problem - wish I had looked in the first place.

Other comments - replacing the fan is far more difficult than it first looks - Replacing the PCB is easy, but the actual replacement part is slightly different to the original, so refer to the wiring diagram on the back of the front cover.

All-in-all its fixed for £248, which is probably what it would have cost to get a boiler man in!!! (You win some, you lose some......)

Davy the hapless DIY'er, November 2009

I have taken off the cover to the heat exchanger and watched the two electrodes as the boiler tries to reset - only one of them seems to be sparking. Is that normal? On a couple of occasions the gas has ignited for a split second. Im not sure if this would help with the diagnosis?

Someone has suggested to me that it may be the fan not functioning properly. Maybe the air pressure switch failing? If this was the case, would this stop the boiler from lighting?

midvale99, November 2009

it sounds like to me there maybe no gas coming through,the gas valve needs checking,or it could be a fault on the flame rectfication side so the cable needs checking including electrode.or pcb

sw plumbing, November 2009