TLDR: Clickbait article misreading an old statute. It is not illegal to do any repairs on your own vehicles inside your own garage in Sacramento.
Longer version:
Reading the original and full text, that the code is for commercial use. I think perhaps the article is being a bit click-baity, and would also note the code, as written, dates back to at least the 2015 revision.
Municipal code likely covers things like inoperative vehicles left in public view, which is a fairly common code in the US, not the Zoning codes. Municipal code would apply to a non-commercial enterprise: and is covered here:
10.52.020 Minor vehicle repair.
It is unlawful and a public nuisance for any person to engage in minor vehicle repair in any residential zone.
A. Upon any vehicle which is not registered to a current occupant of the premises where the work is being performed; or
B. Outside a fully enclosed structure, except that minor vehicle repair may be performed outside a fully enclosed structure where elapsed time between the beginning and end of the repair does not exceed forty-eight (48) hours; or
C. Upon more than two vehicles at one time on the same premises or by the same person. (Prior code § 25.15.401)
" 10.52.030 Major vehicle repair.
A. It is unlawful and a public nuisance for any person to engage in major vehicle repair in a residential zone, unless all of the following conditions exist:
1. The repair is performed within a fully enclosed structure; and
2. The vehicle under repair is registered to a current occupant of the premises; and
3. No more than two vehicles are being repaired at one time on the same premises or by the same person.
B. Subsection A of this section notwithstanding, body painting, other than spot painting, is not permitted in a residential zone. (Prior code § 25.15.402)"
Disclaimer: I am much more familiar with criminal law and am not a California law expert.