BoilerFaultCodesWorcester Bosch 668 Fault Code
The Worcester Bosch 668 fault code means: your boiler has stopped working because the internal fan, which safely exhausts fumes, is not running correctly.. It appears on 1 Worcester Bosch model in our database.
Technical description: Fan
What causes the Worcester Bosch 668 fault?
This fault occurs when the boiler's safety system detects that the internal fan is either spinning too slowly or has stopped moving entirely. Without a functional fan to pull fresh air in and push exhaust gases out, the boiler will prevent ignition to keep your home safe. The most common reasons are a build-up of debris in the fan motor or a total electrical failure of the fan component.
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 668 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 668 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