High Lockout
F14 on Vaillant ecoMAX Pro 28E

Your boiler has shut down because it has detected that the water inside is getting much too hot, which is usually caused by a circulation problem.

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

Central heating flow t° > 95° C

What causes this fault?

This fault occurs when the water inside the boiler heats up too quickly or reaches an unsafe temperature, forcing the system to shut down for safety. The most common reason is a pump failure or a blockage that prevents water from moving through the pipes, causing the heat to build up in one spot rather than being distributed to your radiators.

This fault is frequently seen at the start of autumn when heating systems are turned on for the first time after summer, as pump components can seize during long periods of inactivity.

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

F20View →F24View →

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