I've had the f4/f1 problem on and off loads of times. It's almost invariably the combustion door seal in the end. In fact, mine's just started doing it this year since the boiler was serviced by BG and the combustion door opened to have the exchanger "cleaned". I wish they'd leave the thing sealed up. An old door seal never seals properly once opened but it always takes 2 or 3 visits (with them trying the igniter, etc... to get them to change the seal.
and get boiler serviced, f4 means flame went out during a demand, usually caused by incorrect co2 ratios or faulty burner door seal.
Ian
April 2010
I moved a year ago and have no manual, but have just had the same fault F4 a few days ago - I turned the power off and back on 10 seconds later - everything seems fine at the moment.
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