How much does it cost to fix Heatline error code F6?

Typical repair cost for the Heatline F6 fault is £120-200 including labour.

F6 High

Heatline F6 Fault Code

Q: What does the Heatline F6 fault code mean?

Your boiler is unable to read the temperature correctly because a sensor on the outside of the system is disconnected or faulty, which has caused the boiler to shut down for safety.

The Heatline F6 fault code means: your boiler is unable to read the temperature correctly because a sensor on the outside of the system is disconnected or faulty, which has caused the boiler to shut down for safety.. It appears on 10 Heatline models in our database.

Technical description: External NTC thermistor fault

Typical repair cost £120-200 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Heatline models that show the F6 fault code

Click a model for the full fault code list and model-specific repair notes.

Capriz 24 Repair: £100-180
Capriz 25 System Repair: £120-200
Capriz 25/28 Repair: £70-140
Capriz 28 Repair: £120-200
Capriz Plus Repair: £120-200
Sargon 24 Repair: £90-160
Sargon 28 Repair: £90-160
Solaris Repair: £70-130
Vizo 24 Repair: £90-160
Vizo Plus Repair: £90-160

Source

Heatline F6 fault code information on this page is sourced and cross-checked against the official Heatline service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026