Your boiler's internal computer chip has been disconnected or has developed a communication fault, meaning the system doesn't know which settings to use.

Burner blocked: Boiler coding card missing, faulty or incorrect card inserted

What causes this fault?

This fault occurs when the boiler's main control board loses communication with the small plug-in memory chip that stores the unit's identity and settings. The most common reason is that the chip has vibrated loose, suffered from a hardware failure, or the main circuit board itself can no longer read the data due to a technical glitch.