What can a corrupted cache cause?
It depends on what is corrupted, if it is just the preferences.xml file that is corrupted then it most likely prevents you from starting the game, or loading into the game for that, often resulting in you being stuck in loading the garage.
What can be corrupted?
There are a few things that can be corrupted, the most common one is the preferences.xml file, but it doesnt end there. As mentioned in What does the cache do? the cache is also used by various mods to store their own settings.
What can it cause?
If the cache is corrupted it can cause the game to crash, or not load at all. This is because the game is unable to load the settings it needs to run the game properly.
This also includes mods, if the cache is corrupted the mods might not work properly, or not work at all or even cause the game to crash.
How to fix it?
The easiest way to fix a corrupted cache is to delete it, as described in How to delete the Cache?. This will force the game to create a new cache with the default settings, which should fix the issue.