BoilerFaultCodesWorcester Bosch EE9 Fault Code
The Worcester Bosch EE9 fault code means: your boiler has detected a communication issue or a fault with one of its internal ignition electrodes, meaning it cannot safely light the burner.. It appears on 1 Worcester Bosch model in our database.
Technical description: Second electrode
What causes the Worcester Bosch EE9 fault?
This fault occurs when the boiler's control system loses contact with the secondary electrode responsible for creating the spark to light the gas. It is usually caused by the electrode becoming worn out, cracked, or covered in carbon deposits, which prevents it from sending the correct electrical signal back to 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 EE9 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch EE9 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