BoilerFaultCodesWorcester Bosch Fault 54 / 145 Fault Code
Also written as FAULT54145 — same fault.
The Worcester Bosch Fault 54 / 145 fault code means: your boiler is warning you that your solar-heated water tank hasn't reached a high enough temperature to safely kill off any potential bacteria.. It appears on 2 Worcester Bosch models in our database.
Technical description: Temperature for thermal disinfection not reached in solar cylinder: Maximum temperature for solar cylinder too low.
What causes the Worcester Bosch Fault 54 / 145 fault?
This fault occurs when the water in your solar cylinder hasn't reached the high temperature required to automatically sterilize the tank. It usually means the solar panels haven't been able to heat the water sufficiently or the temperature sensor is accurately reporting that the thermal disinfection cycle failed to complete. The most common reasons are a lack of strong sunlight, a faulty sensor, or an issue with the solar pump not circulating fluid correctly.
This warning is more common during the winter months or periods of heavy cloud cover when there is insufficient solar energy to heat the cylinder to the required disinfection temperature.
DIY fix possible
Check if your solar thermal controls are switched onWait for a period of stronger sunlight to allow the tank to heat naturallyConsult your solar control panel manual to ensure the target disinfection temperature is set high enough (usually 60°C or above)
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Gas Safe Register →Worcester Bosch models that show the Fault 54 / 145 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Fault 54 / 145 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026