I don't know about the G8 in any way. I just have had similar experience with ABS sensor wires. Especially when lifting trucks for example, if I wire gets tweaked, but is still connected, you sometimes cant see any damage. The outer sheath of the senor wire will be good, but every now and then itll throw some lights on the dash. Then the next time theyre all gone.
Its just enough to throw a code to the computer and then itll clear itself for next time. Just annoying.
Again...It might not even have pad sensors...That was just spitballing a maybe. If they exist...check them close...make sure they aren't gunked.