BoilerFaultCodesWorcester Bosch Alert Fault Code
Also written as ALERT — same fault.
The Worcester Bosch Alert fault code means: your boiler has detected an internal error and is waiting for you to look at the display to reveal the specific fault code causing the problem.. It appears on 1 Worcester Bosch model in our database.
Technical description: Displays during a fault condition with diagnostic and status code
What causes the Worcester Bosch Alert fault?
The 'Alert' notification appears when the boiler’s central brain detects that a specific component is no longer operating within its safe or expected limits. This usually happens because an internal part, like a sensor or the fan, has either failed completely or is sending inconsistent data to the control board. It acts as a protective 'blanket' message that stops the boiler to prevent further damage until the underlying technical issue is identified.
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 Alert fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch Alert 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