Fault C3 — Communication fault with extension AM1

What does C3 mean?

The boiler is in control mode but detects a communication fault with the extension AM1. This module is part of the boiler's control system, and a fault prevents proper operation.

• Loose or damaged connections to extension AM1
• Faulty extension AM1 module

Click steps to track your progress.

1. 1

   Check all physical connections to the extension AM1 module.

2. 2

   Ensure the wiring is secure and undamaged.

3. 3

   If connections are good, the extension AM1 module may be faulty and require replacement.

4. 4

   Contact a qualified service technician for further investigation.