High Lockout
F13 on Vaillant ecoMAX Pro 28E

Your boiler's computer brain has encountered a serious communication error and can no longer control the heating system safely.

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

Main board fault

What causes this fault?

This fault occurs when the boiler's internal computer experiences a major electrical short or a critical component failure on the control board. The most common reason is general wear and tear of the electrical circuits over time, or pulse damage caused by a power surge.

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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