High Lockout
0 1. on Remeha Quinta Ace 65

Your boiler has lost power to its internal electrical control circuit, meaning it cannot communicate with its parts or operate at all.

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

Short-circuit 24V: Check wiring.

What causes this fault?

This fault occurs when there is an electrical 'short' in the low-voltage circuit that powers the boiler's sensors and internal controls. It is usually caused by water leaking onto electrical components or a damaged wire touching the metal casing, which forces the boiler to shut down to prevent damage to the main circuit board.

This issue is slightly more common during the autumn when heating systems are first turned back on, as pinhole leaks or dampness may have developed around the electrical sensors over the summer months.

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 won't turn on — 9-step checklist

Work through these before the call-out.

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 →