This is what the document says about occupancy.
It doesn't clearly say that you can rent it out but sounds like it.
You should check with the fremont planning department.
(4) Occupancy: A secondary dwelling unit may be occupied as a separate single-family
dwelling only if the legal owner of the lot occupies one of the dwellings located on the
lot; otherwise, the secondary dwelling unit and the dwelling to which it is accessory
shall. be occupied as if they were one single-family dwelling. Nothing in this section
prohibits the secondary dwelling unit or principal dwelling on the lot from remaining
vacant. The city manager shall require recordation of a deed restriction setting forth
this occupancy requirement before issuing a building permit.
I have not heard of such a restriction; however, I would contact the City of Fremont Planning Division at (510) 494-4440; and/or, here's their address:
39550 Liberty St., Fremont, CA 94538
If you are suffering from insomnia you can also search Fremont's Municipal Code as well:
Please come back and post what the City tells you ....
Contact the city for additional information.