High Lockout
270 on Baxi EcoBlue Advance

Your boiler has detected that it is heating up too quickly without enough water circulating through it, causing it to shut down to prevent overheating.

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

Dry fire

What causes this fault?

This fault occurs when the heat exchanger becomes too hot too quickly because there isn't enough water moving through the system to carry the heat away. The most common reasons are a seized internal pump, a blockage caused by sludge buildup, or air trapped within the boiler's internal pipework.

This issue is frequently seen when turning the heating back on for the first time in autumn, as pump components can seize up after being idle throughout the summer.

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 keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

Banging / kettling / whistling noise

Each noise points to a different fault.

Read →

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →