High Lockout
F012 on Intergas Xtreme / Xclusive

Your boiler has detected a problem with its internal temperature sensor, which means it cannot accurately monitor the water heat and has stopped working for safety.

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 5 fault

What causes this fault?

This fault occurs when the boiler's internal control board loses communication with the temperature sensor or receives an illogical reading. The most common reason is that the sensor's electrical resistance has moved out of range due to age, or the wiring connecting the sensor to the main board has become loose or damaged.

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

F010View →F011View →

Related guides you might find useful

Boiler keeps cutting out

Lockout fault with a reset-needed pattern.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →