High Lockout
F000 on Intergas Xtreme / Xclusive

Your boiler has stopped working because one of its internal sensors is sending an incorrect signals or has disconnected, preventing it from heating your water safely.

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

Sensor defect

What causes this fault?

This fault occurs when the boiler's control board loses communication with the sensors that monitor water temperature. It is usually caused by a physical break in the internal wiring or a sensor that has reached the end of its life and is sending unreadable data. Because the boiler can no longer confirm the water is at a safe temperature, it shuts down immediately as a safety 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 fault codes

F001View →F002View →F003View →

Related guides you might find useful

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 →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →