How much does it cost to fix Heatline error code F3?

Typical repair cost for the Heatline F3 fault is £120-180 including labour.

F3 High

Heatline F3 Fault Code

Q: What does the Heatline F3 fault code mean?

Your boiler is struggling to accurately detect the temperature of your hot water, which means it will likely stop producing hot water until the faulty sensor is replaced.

The Heatline F3 fault code means: your boiler is struggling to accurately detect the temperature of your hot water, which means it will likely stop producing hot water until the faulty sensor is replaced.. It appears on 10 Heatline models in our database.

Technical description: Domestic hot water sensor (NTC) fault

Typical repair cost £120-180 (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 F3 fault code

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

Capriz 24 Repair: £120-200
Capriz 25 System Repair: £120-200
Capriz 25/28 Repair: £90-160
Capriz 28 Repair: £120-180
Capriz Plus Repair: £120-200
Sargon 24 Repair: £90-160
Sargon 28 Repair: £90-160
Solaris Repair: £180-450
Vizo 24 Repair: £90-160
Vizo Plus Repair: £90-160

Source

Heatline F3 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