Determining the transmit frequency of a key fob
Almost certainly 315MHz.

There isn't a visible crystal on the PCB. The 433MHz frequency used is actually just one frequency at 433.82MHz as defined by the FCC and numerous other agencies throughout the world. To transmit with adequate accuracy always requires a crystal, an IC by itself can't do it.

A device using &quot;315MHz&quot; actually just has to fit in a band that goes all the way from 270MHz up to 390MHz so accuracy to keep within the band is not a problem, but it has to be accurate enough to stay within the acceptable range of the receiver which depends on its design. A simple super-regenerative receiver has a wide acceptance range.
A superhet receiver has a much-narrower bandwidth but some receivers are designed to sweep over a range to make them compatible with transmitters that are not very accurate (such as this one).

Asking Google to search &quot;6sc2 remote&quot; comes up with a number of links that are all pointing to 315MHz devices. Unfortunately no datasheets.