High Lockout
31 on Alpha E-Tec Regular

Your boiler has lost its connection with the thermostat or control panel, meaning it cannot receive instructions to turn on or off.

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

Loss of communication with external control (Alpha Climatic)

What causes this fault?

This fault occurs when the boiler and your thermostat can no longer 'talk' to each other, often due to physical interference or a hardware failure. The most common reason is that the batteries in your room thermostat have died or the wireless receiver attached to the boiler has lost its signal. In some cases, it may be caused by a faulty circuit board that is unable to process incoming signals from your controls.

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.

Find a Gas Safe engineer
Search the official register →

Related guides you might find useful

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →