High Lockout
HA on Ideal Esprit HE

Your boiler has developed a communication or hardware circuit error that has caused it to stop providing both heating and hot water.

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

Boiler is not working for central heating or hot water and the display shows ‘HHHHH:::::AAAAA ’ (flashing).

What causes this fault?

This fault occurs when the boiler's internal communication system suffers a total breakdown, essentially meaning the different electronic parts can no longer 'talk' to each other. The most common reason is a physical failure within the main circuit board or a malfunction in the control knobs that prevents the boiler from receiving instructions. Because the brain of the boiler cannot verify the system is safe or functional, it shuts down entirely as a precaution.

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

No hot water but heating works

Almost always a stuck diverter valve on combis.

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 →