High Lockout
b7 on Viessmann Vitodens 222-W

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.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

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.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

b0View →b8View →

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