High Lockout
1073 W on Worcester Bosch Greenstar 8000 Life/Style

Your boiler has detected an electrical fault with its main temperature sensor, which means it cannot safely monitor how hot the water is and has stopped working as a precaution.

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 of the flow temperature sensor – the temperature sensor may need replacing

What causes this fault?

This fault occurs when the boiler's control set loses the ability to correctly read signals from the flow temperature sensor. The most common reason is that the internal sensor has suffered a technical failure or the wiring connecting it to the main circuit board has become damaged or loose. Because the boiler no longer knows how hot the water is, it shuts down to prevent any risk of overheating.

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

228View →

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 →