How much does it cost to fix Heatline error code 90 Flashing?

Typical repair cost for the Heatline 90 Flashing fault is £120-250 including labour.

90 Flashing High

Heatline 90 Flashing Fault Code

Q: What does the Heatline 90 Flashing fault code mean?

Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or safety hazards.

Also written as 90FLASHING — same fault.

The Heatline 90 Flashing fault code means: your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage or safety hazards.. It appears on 2 Heatline models in our database.

Technical description: Overheat Thermostat

Typical repair cost £120-250 (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 90 Flashing fault code

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

Source

Heatline 90 Flashing 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