EA = flame failure
You would have to test each component involved in IGNITION SEQUENCE
Gas supply
Gas valve
Fan
Spark generator
Ignition & detection electrodes
Air gas mixture
Pcb
Flue
& finally the CONDENSATE TRAP
You will need
Multimeter
Manometer
Flue gas analyser
& test procedures which can be acquired by ringing Worcester tech
Asbestos
August 2017