The transmitter, a light relay of the more powerful Mendip transmitter in Somerset, went off air at 5.13am with engineers currently on scene, working to correct the situation.
It is not yet known whether the fault is with the Bath relay itself or the signal being produced from Mendip.
All other multiplexes are still available to view on the limited service of the Bath transmitter, though the BBC multiplex PSB1 is currently offline.
Most of Bath currently receives signals from the Mendip transmitter directly rather than through Bath, allowing for a greater number of channels to be received.