Set Appliance State:

Ensure no demands
Ensure appliance is cool
ECO mode ON (ECO in display)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Appliance should do a short self check (approx. 5 seconds) then enter standby, pump should not be running and boiler should not attempt to fire.
If a fault code is shown choose that option below,
failure to do so will lead to misdiagnosis.
Note:
If display shows "FH" and pump starts pulsing then
PCB parameters are set wrong click HERE.