Your boiler is failing to ignite because it cannot detect a flame or receive the necessary gas supply to start up.

Technical description

Fault:Ignitionunsuccessfulwhenstartingup | Gasmeterdefectiveorgaspressuremonitorhastriggered,airingas,gasflowpressuretoolow,thermalisolatordevice(TAE)hastriggered,incorrectgasrestrictor,incorrectsparegasvalve,faultonthegasvalve,multipleplugonPCBincorrectlypluggedin,breakincableharness,ignitionsystem(ignitiontransformer,ignitioncable,ignitionplug,ignitionelectrode)defective,ionisationcurrentinterrupted(cable,electrode),incorrectearthingofproduct,electronicsdefective