My Miicron boilers Led lights flash all the time when turned on, the fan starts but the boiler doesn't fire up at all. I've replaced the PCB but it hasn't changed a thing, might it be a faulty thermistor?
I would appreciate any advise. Many Thanks.

Barry, May 2010

If LH Light lit & RH light not / PCB or GAS Valve Faullt.
LH light not lit & RH Light on / Burner lit
LH light flashing fast & RH light not on / PCB Fault
Both lights lit slow flash, simutaneous / Polarity incorrect
RH light slow flash & LH light fast flash / THermistor Fault
RH Light Fast Flash & LH slow flash / APS swithch fault
Both lights slow flash Alternating / PCBFault, Gas Valve passing, Flame sense probe shorting to earth.
RH light on & LH light slow flash / PCB Fault
RH light on & LH light fast flash/ Ignition Lockout
Flash slow 2 hz
flash fast 8 hz

ECF1878, July 2010