Low
d4 on Alpha E-Tec NXS

Your boiler is signalling that the temperature setting for your radiators is currently being adjusted or is not being correctly detected.

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

Central heating set point temperature

Shared across the Alpha E-Tec range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
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 external thermostat or boiler controller to ensure the desired temperature is set correctly.Restart the boiler by turning it off at the wall or fuse spur for 30 seconds and then switching it back on.Verify that all radiator valves are fully open to allow the system to reach the requested temperature.

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Related fault codes

d1View →d5View →

All 54 fault codes on the E-Tec NXS

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

010203040506081012151620232429313738434547516061707576d0d1d2d3d5d6d7d8d9d10d11d12d13d14d15d16d17d18d19d20d21d22E03E12E20E38

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