My ICOS HE15 boiler is not working and the display is flashing F and L... Please help as its getting cold!

N Townsend, November 2011

if voltage present at the gas valve and gas is present then its not the gas valve, if the spark electrode is tested with an ohms meter then it not
faulty or if voltage is present at the spark electrode and sparks but boiler does not fire then it leaves the fault at the v9 pcb check for voltage at the pcb on gas valve connections and spark electrode fault on pcb could well be the triac or the ac tracks off the double sided pcb under the primary & secondary pcb transformer.........???????

SID, December 2023

repair the pcb replace the 6 pin optocoupler triac

SID, December 2023

Alternating FL - flame loss.
Reset by pressing small button for three seconds.
If boiler will not reset then the V9 control box is faulty.
If it resets and attempts to start - check for voltage at gas valve and at ignition generator, verify gas supply is ok, verify condense trap is not blocked.
If there is voltage at gas valve it may be faulty, if there is voltage at ign gen it may be faulty. Usually the ignition spark is audible , top right of heat engine.
Verify fan is running. FL is a general fault to do with flame loss and can be caused by any of the above being faulty.

Jonny Graham, November 2011