BoilerFaultCodesWorcester Bosch Fault 02 / 40 Fault Code
Also written as FAULT0240 — same fault.
The Worcester Bosch Fault 02 / 40 fault code means: your boiler's computer brain has become confused and is no longer recognising its own internal components.. It appears on 1 Worcester Bosch model in our database.
Technical description: Internal fault: Incorrect module type detected.
What causes the Worcester Bosch Fault 02 / 40 fault?
This fault occurs when the boiler's main control board loses communication with the unique memory chip that contains the unit's specific settings. It is usually caused by a physical hardware failure within the electronics or a loose connection on the circuit board itself, preventing the boiler from knowing which model it is supposed to be. In some cases, a significant electrical surge can also corrupt this internal data, causing the system to shut down for safety.
This fault is often seen after heavy summer thunderstorms, as power surges from lightning strikes can damage the sensitive electronic components on the main circuit board.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Worcester Bosch models that show the Fault 02 / 40 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Fault 02 / 40 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