Fault C2 — Communication fault with solar control unit or Vitosolic

What does C2 mean?

The boiler is in control mode but detects a communication fault with either the solar control unit or the Vitosolic. This indicates an issue with the communication line to the solar thermal system components.

• Faulty solar control unit
• Faulty Vitosolic unit
• Loose or damaged communication wiring between the boiler and solar components

Click steps to track your progress.

1. 1

   Check the solar control unit or Vitosolic for any error messages or indicators.

2. 2

   Inspect the communication wiring connecting the solar control unit/Vitosolic to the boiler for damage or loose connections.

3. 3

   Ensure both units have power.

4. 4

   If problems persist, a qualified technician should check the solar control or Vitosolic unit.