Low
d.16 on Glow-worm Ultimate3 Combi

Your boiler is currently receiving a signal from your room thermostat telling it to switch off or stay idle, so it is not firing up for heating right now.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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.

What the manual says

Manufacturer manual

Statusofthe24Vroomthermostat

From this model's manual
Verified against the Glow Worm/Glow Worm Ultimate3 Combi installation & service manual, page 41.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check your room thermostat and turn the target temperature higher than the current room temperatureEnsure your thermostat batteries are not flatCheck if your thermostat is set to 'off' or 'summer mode' and switch it to heating mode

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Related fault codes

d.15View →d.17View →

All 170 fault codes on the Ultimate3 Combi

Seeing a different code? Every code this model can display, in one place.

d.00d.01d.02d.04d.05d.06d.07d.08d.09d.10d.11d.13d.14d.15d.17d.18d.19d.20d.21d.22d.23d.24d.25d.27d.28d.31d.33d.34d.35d.36d.39d.40d.41d.43d.45d.47d.50d.51d.58d.60d.61d.62d.64d.65d.66d.67d.68d.69d.70d.71d.73d.75d.77d.80d.81d.82d.83d.84d.85d.88d.90d.91d.93d.94d.95d.96F.00F.01F.10F.11F.13F.20F.22F.23F.24F.25F.27F.28F.29F.32F.49F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.77F.78F.83F.84F.85F.86F.87F.88F.89F.97F2F22Main burner does not lightNeon 1 lit (No)neon 1 not litNeon 2 lit (No)neon 2 not litNeon 3 lit (No)neon 3 not litNeon 4 lit (No)neon 4 not litP.01P.02P.03P.04P.05P.06P.07Pilot does not lightPilot does not stay alightPump OverrunS.0S.01S.02S.03S.04S.05S.06S.07S.08S.10S.11S.13S.14S.15S.16S.17S.20S.21S.22S.23S.24S.25S.26S.27S.28S.30S.31S.32S.33S.34S.39S.41S.42S.46S.53S.54S.88S.91S.96S.97S.98S.99S.108S.109

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