Your boiler is simply letting you know that it is due for its routine annual service soon.

Maintenance indicator – number of hours until the next maintenance

What causes this fault?

This code is triggered because your boiler has a built-in timer or run-hour counter that tracks how long it has been since its last professional inspection. It is not a mechanical failure but rather a proactive reminder set by an engineer to ensure the appliance remains safe and efficient. Once the pre-set time limit is reached, the system displays this notification to nudge you to book your annual maintenance.