d.41 Medium

Heatline d.41 Fault Code

Also written as D41 — same fault.

The Heatline d.41 fault code means: your boiler is struggling to detect the temperature of the water returning to it from your radiators, which may cause it to turn off to prevent overheating.. It appears on 2 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: Heating return temperature
Typical repair cost £120-220 (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 d.41 fault code

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

Source

Heatline d.41 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 31 August 2026