Low Information
C4 on Remeha Avanta Plus 35c

Your boiler is simply notifying you that it is currently busy heating your tap water and there is no actual fault.

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

Boiler is operating for DHW

What causes this fault?

This code appears when the boiler detects a demand for hot water from a tap or shower. It is a status indicator rather than a malfunction, showing that the internal components are currently prioritising your hot water over central heating. Once the tap is turned off, the code should disappear as the boiler returns to its normal standby or heating mode.

DIY fix possible

No action is required as this is a normal status message.Wait for the hot water tap to be turned off and the boiler will return to its normal standby or heating mode.

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