High Lockout
A05 on Ferroli BlueHelix Pro 25C

Your boiler has stopped working because the internal fan, which safely removes waste gases, is not spinning at the correct speed.

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

Fan error

What causes this fault?

This fault occurs when the boiler's control board cannot detect that the fan is spinning at the required speed to safely clear exhaust gases. The most common reason is a mechanical failure within the fan motor or a communication issue caused by a damaged wiring harness or a fault on the main circuit board.

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

Banging / kettling / whistling noise

Each noise points to a different fault.

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 →