70 Medium

Heatline 70 Fault Code

The Heatline 70 fault code means: your boiler is having trouble detecting the temperature of the water used for your taps and shower, so it has stopped heating your hot water to prevent it from getting too hot.. It appears on 3 Heatline models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Fault on DHW sensor
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 70 fault code

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

Source

Heatline 70 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 7 July 2026