d.16 Low

Glow-worm d.16 Fault Code

Also written as D16 — same fault.

The Glow-worm d.16 fault code means: your boiler is currently receiving a signal from your thermostat that your home has reached the desired temperature, so it is waiting for a command to start heating again.. It appears on 11 Glow-worm models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Status of the 24V room thermostat (ON/OFF)

DIY fix possible

Locate your room thermostat or smart controllerTurn the target temperature up higher than the current room temperatureCheck if the boiler fires up and the fault code clears

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Glow-worm models that show the d.16 fault code

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

Source

Glow-worm d.16 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026