HEX: 01 - Defective control unit

Fault Details:

• Defective ECU (control unit)

• Incorrect end-of-line programming

• Coolant temperature sensor failure (for water heaters)

Recommended Solution:

• Replace the ECU (control unit)

Note: Fault code meanings can vary depending on the model and controller. If you’re unsure, contact Heatso directly for assistance.