BoilerFaultCodesWorcester Bosch 79 Fault Code
The Worcester Bosch 79 fault code means: your boiler has lost its electrical supply and won't turn on, meaning it cannot provide any heating or hot water.. It appears on 1 Worcester Bosch model in our database.
Technical description: No power to boiler
What causes the Worcester Bosch 79 fault?
This fault occurs when the electrical circuit feeding the boiler is interrupted, meaning the control system has no power to operate. The most common reasons are a blown fuse in the external wall switch, a tripped circuit breaker in your fuse box, or a failure of the internal components that manage electricity within the boiler itself.
This fault is more common during the winter months when heavy electrical demand or local power surges can cause external fuses or circuit breakers to trip.
DIY fix possible
Check if other appliances in the house have powerInspect your home's main fuse box (consumer unit) for any tripped switchesCheck the fused spur switch near the boiler to ensure it hasn't been turned off or the fuse hasn't blown
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Gas Safe Register →Worcester Bosch models that show the 79 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Worcester Bosch 79 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