High Lockout
58:0 on Viessmann Vitodens 300-W

Your boiler is struggling to heat your hot water tank because it cannot detect or communicate with a required component or sensor.

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

Without auxiliary function for DHW loading

What causes this fault?

This fault occurs when the boiler's control system loses its connection to the sensor responsible for monitoring your hot water cylinder. The most common cause is a faulty temperature probe or a break in the wiring that prevents the boiler from knowing how hot your water is. Without this information, the boiler stops heating the water as a safety precaution to prevent overheating.

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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