BoilerFaultCodesWorcester Bosch Internal error. Fault Code
Also written as INTERNALERROR — same fault.
The Worcester Bosch Internal error. fault code means: your boiler has detected an internal computer error, meaning it has safely shut itself down to prevent potential damage to its electronic systems.. It appears on 4 Worcester Bosch models in our database.
Technical description: Check electrical connector contacts, programmer interface module ignition leads are not loose; replace pcb if necessary.
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 Internal error. fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Internal error. 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 532 / 537 / 542 manual (PDF)
- Worcester Bosch Greenstar 25CDi manual (PDF)
- Worcester Bosch Greenstar i manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026