High Lockout
31E on Ravenheat HE 80/90 / 25-30s

Your boiler is having trouble 'talking' to your smart thermostat or external heater controls, meaning it may not 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

OpenTherm (OT) communication error

What causes this fault?

This fault occurs when the digital connection between your external thermostat and the boiler's internal computer is broken or interrupted. The most common reasons are loose wiring connections at either end of the control cable or a electronic synchronization failure between the two devices.

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

21EView →

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