Adjust, Service, Repair or Replace as necessary
Isolate Mains Power to appliance as per TOPs P4
Isolate Water and Gas as appropriate

Location:
Ensure that the gas valve harness is fitted correctly / securely before ordering a replacement combustion control unit as the comm error may just be due to a poor connection.
Upon completion of the fault diagnostics carry out final electrical safety tests and checks as per TOPs (C6).

Refer to ADAPT for further information.

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Phone - 722429
or Email - Diaglab@britishgas.co.uk