4 green flashes Low

Baxi 4 green flashes Fault Code

Also written as 4GREENFLASHES — same fault.

The Baxi 4 green flashes fault code means: your boiler is having a temporary 'handshake' issue between its internal electronic brains, but it should fix itself automatically.. It appears on 22 Baxi 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: Communication error between printed circuit board (PCB) and control. Temporary error, will self reset.

What causes the Baxi 4 green flashes fault?

This fault occurs when the internal control panel and the main electronic circuit board momentarily lose their connection with each other. It is often caused by a minor electrical glitch or a brief delay in data being sent between these two components. In most cases, it is a temporary hiccup in the boiler's internal computer system rather than a mechanical failure.

Typical repair cost £0-120 (including labour)

DIY fix possible

Wait for the boiler to self-reset as this is often a temporary glitchIf the flashing continues, turn the selector switch to 'Reset' for five secondsMonitor the boiler to see if the green flashes return

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Baxi models that show the 4 green flashes fault code

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

Source

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

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