High Lockout
E07 on Viessmann Vitodens 100-W

Your boiler is unable to light because the internal fan isn't spinning fast enough to clear the system or provide the correct air flow.

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 does not start. Fan speed too low during burner start.

What causes this fault?

This fault occurs when the boiler's control system detects that the fan isn't reaching the necessary speed to safely clear the combustion chamber and start the burner. The most common reasons are a build-up of dust or debris slowing the fan's rotation, a failing motor, or a communication error where the main control board can no longer regulate the fan's power.

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

E08View →

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