4 green flashes Low
Your boiler is having a temporary 'handshake' issue between its internal electronic brains, but it should fix itself automatically.
Technical description: Communication error between printed circuit board (PCB) and control. Temporary error, will self reset.
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
Protect yourself from future repair bills
A boiler cover plan would cover faults like 4 green flashes — no call-out fees, no surprises.
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Parts commonly replaced
- None (usually self-correcting)
- Printed Circuit Board (PCB)
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