High Lockout
06 on Glow-worm 30ci Plus

Your boiler has stopped working because a sensor that measures the temperature of the water leaving the unit has failed or has a poor connection.

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

Central heating flow NTC fault

What causes this fault?

This fault occurs when the boiler's internal computer can no longer read the temperature of the water being sent to your radiators. The most common reason is that the sensor has either suffered an internal electrical failure or the wiring connecting it to the main control board has become loose or corroded. Because the boiler cannot safely monitor how hot the water is getting, it shuts down 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

05View →12View →

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 →