Please help, i'm now into my 4th week of no CH or DHW and about to tear my hair out! My brother-in-law is Gas Safe registered fitter and has been trying to solve my problem with Ideal Mini C24 boiler, which he himself fitted in late 2006. Initial replaced pump, and following diagnosis by Ideal technical helpline, replaced PCB. Everything worked fine for approx 6 hours then boiler locked out, was reset, but now fails to ignite. Leds point to "Lack of burner ignition(no ignition signal from the full sequence ignition device)" and confirmed again by Ideal by email as unable to call in their working hours. Their first response was as follows : The LEDs do indicate ignition lockout, now this can be caused by air pressure switch not moving over, ignition pcb, ignition probes and gas valve. To enable us to correctly diagnose the fault we would need to know how far in the sequence the boiler gets to before locking out. If your engineer could call from site we can go through fault finding checks and advise the cause" Unfortunetely, my brother in law is working outside Glasgow during the day and is unable to be onsite while the technical helpline is open (closes at 5pm) so asked us to email a reply : ..." the boiler goes full cycle to ignite and it wont let gas through to ignite, it then locks out and red LED shows with red lock out light, when reset the same happens again." Their reply was as follows: "...carry out the following checks as the boiler is going through its ignition sequence. When the fan runs ensure there is 240v on the dark blue wire from the air pressure switch (normally open side), after the power goes through the overheat stat on the right hand side of the heat exchanger. With voltage present at both of these points ignition takes place and 240v is passes to the gas valve this lifts at ignition rate of 6mb. Detection then takes place and the boiler will increase to full rate." Bro-in-law came down tonight, but didnt have multimeter to check voltage. Check all parts, but noticed a resistor (R24) on pcb looks possibly burnt out. However, on comparing the new pcb with original pcb, original had no resistor at R24. My dad is more electrical minded and brought a multimeter over tonight, but unsure exactly where he should be testing. He checked voltage getting to gas valve - showing 100 - 130v ??! I have also purchased new electrodes (2 ignition and detection) as wire from one looked damaged (cut and reattached via connection block) - but now unsure if probes are to blame as boiler attempts to light (click click sounds and can see spark, similar to cooker ignition sound). Any ideas where we go from here? have only spent £70 so far, and being only 4 yrs old, i would hope its repairable and not new boiler needed. I have a young family and cannot afford this outlay, but also cannot continue with no heating with temp dropping outside recently. Sorry for long post! Very frustrated home owner in need of assistance - or will i have to bite the bullet and ask Ideal out to look at it? If so, can anyone advise the likely cost of this?