Fault 53 Codes 125 or 128 — Temperature sensor T1 fitted in wrong location

What does Fault 53 125-128 mean?

The Worcester Bosch Greenstar CDi Boiler displays Fault 53 with code 125 or 128, indicating that the collector temperature sensor (T1) has been fitted in an incorrect location, specifically on the collector array inlet instead of the outlet.

• Collector temperature sensor (T1) is installed on the inlet pipe
• Incorrect positioning of the sensor during installation

Click steps to track your progress.

1. 1

   Turn off the power to the boiler and solar system.

2. 2

   Relocate the collector temperature sensor (T1) from the collector array inlet.

3. 3

   Fit the sensor close to the collector array outlet as specified in the installation instructions.

4. 4

   Restore power and check if the fault clears. If it persists, contact a qualified heating engineer.