BoilerFaultCodesWorcester Bosch 218 Fault Code
The Worcester Bosch 218 fault code means: your boiler has detected that the water inside the system is becoming dangerously hot and has shut itself down to prevent damage or overheating.. It appears on 5 Worcester Bosch models in our database.
Technical description: Flow temperature too high
What causes the Worcester Bosch 218 fault?
This fault occurs when the boiler's main control board experiences a data processing failure or loses connection with internal sensors. It is typically caused by a genuine electronic failure within the computer chip or electrical interference disrupting the signal between components. While a simple reset may temporarily clear it, the code usually indicates that the internal hardware has reached the end of its reliable lifespan.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Worcester Bosch models that show the 218 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 218 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.
- Worcester Bosch 24/28/35 CDi MkII manual (PDF)
- Worcester Bosch Greenstar 12i System manual (PDF)
- Worcester Bosch Greenstar 28CDi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026