High Lockout
AL34 on Vokera Mynute 23E

Your boiler has stopped working because it cannot correctly detect if the internal fan is spinning at the right speed to safely clear away exhaust fumes.

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

Fan tacho signal fault

What causes this fault?

This fault occurs when the boiler's main computer loses track of how fast the internal fan is spinning, which is a vital safety check. It is typically caused by a buildup of dust and debris slowing the motor down, or a failure in the electronic sensor that reports the speed back to the system. If the fan can't be verified as working correctly, the boiler shuts down to prevent dangerous exhaust gases from staying inside the unit.

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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