S.30 Low

British Gas S.30 Fault Code

Also written as S30 — same fault.

The British Gas S.30 fault code means: your boiler is working fine, but it isn't receiving a signal from your room thermostat or programmer telling it to turn on.. It appears on 1 British Gas model 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: No Heating demand from external controls 230V. Check wiring in external controller. Check wiring at Installer Interface.
Typical repair cost £0-120 (including labour)

DIY fix possible

Check that your room thermostat is turned up higher than the current room temperature.Ensure your central heating programmer or timer is set to 'ON' or 'AUTO'.Replace the batteries in your wireless room thermostat if the display is blank or fading.Check that the internet gateway is connected if you use a smart system like Hive or Nest.

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British Gas models that show the S.30 fault code

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

Source

British Gas S.30 fault code information on this page is sourced and cross-checked against the official British Gas service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026