Fault C1 — Communication fault with extension EA1

What does C1 mean?

The boiler is in control mode but detects a communication fault with the extension EA1. This extension handles various control functions like external heating program changeover, external blocking, and external demand.

• Loose or damaged connections to extension EA1
• Faulty extension EA1 module

Click steps to track your progress.

1. 1

   Check all physical connections to the extension EA1 module.

2. 2

   Ensure the wiring is secure and undamaged.

3. 3

   If connections are good, the extension EA1 module may be faulty and require replacement.

4. 4

   Contact a qualified service technician for further investigation.