Remedy
Note: Front cover sealing issues can cause this fault.
▶ Refer to blocking errors(s) that lead to this locking error. Check the fault history on the appliance.
▶ Possibly the purging of the gas pipe is incomplete.
▶ It could also indicate a wide variety of issues such as pipework undersized or gas pressure dropping off, incorrectly routed condens drains, incorrectly sited flues, incorrectly wired etc.