High Lockout
39 on Ideal Maximiser SE

Your boiler has lost communication with your wall thermostat, meaning it cannot receive the signal to turn on your heating.

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

Check the ModuLine room thermostat. If the thermostat functions properly, the control panel is defective. Replace the control panel.

What causes this fault?

This fault occurs when the digital communication link between your wall controller and the boiler's internal computer is broken. The most common reason is a wiring failure at the connections or an internal electronic failure within the ModuLine thermostat itself, which prevents the boiler from receiving the command to fire up.

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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