Your boiler's internal computer has detected a safety control failure and has locked itself down as a precaution.

Safety relay does not close

What causes this fault?

This fault occurs when the boiler's internal computer tries to engage a safety switch but detects that it has failed to close. The most common reason is a mechanical or electrical failure within the main circuit board, which prevents the system from confirming it is safe to ignite the burner. Because this involves a critical safety check, the boiler will prevent all operation to protect the household.