High Lockout
RED LED BLINKS on Vokera Compact HE

Your boiler has likely overheated or has an issue with its internal fan system, causing it to shut down for safety.

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

High limit thermostat fault or air flow switch fault

What causes this fault?

This fault occurs when the boiler's internal components detect that the unit is either getting too hot or that the fan isn't safely clearing waste gases. The most common reasons are a blockage in the flue, a failing circulation pump, or a simple mechanical failure of the safety sensors themselves.

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 fault codes

RED LED SOLIDView →GREEN LED BLINKSView →

Related guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Boiler keeps losing pressure

Six most common causes of dropping pressure.

Read →

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →