Fault 02 Code 100 — Internal fault, ISM not responding

What does Fault 02 100 mean?

The Worcester Bosch Greenstar CDi Boiler displays Fault 02 with code 100, indicating an internal fault where the ISM (Internal System Module) is not responding to commands or communicating correctly.

• Faulty BUS connection to the ISM
• Circuit break affecting ISM communication
• Faulty ISM module

Click steps to track your progress.

1. 1

   Check the physical connections to the ISM for any signs of damage or looseness.

2. 2

   Ensure all wiring related to the ISM is secure and intact.

3. 3

   If the fault persists, contact a qualified heating engineer to inspect the BUS connection or replace the ISM.