LED 4 Low

Myson LED 4 Fault Code

Also written as LED4 — same fault.

The Myson LED 4 fault code means: your boiler is correctly telling you that it has received a signal from your thermostat and is currently turning on the pump to circulate hot water to your radiators.. It appears on 3 Myson 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: On when there is a demand for the central heating pump.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Myson models that show the LED 4 fault code

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

Source

Myson LED 4 fault code information on this page is sourced and cross-checked against the official Myson service / installation manuals for each affected model.

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