2018 SS 1LE with 7k miles. Was planning on selling it this week. Drove fine two days ago for the test drive. This morning I start it (It has a battery that is less than 6 months old) and I get a "service rear axle" message. I googled it and seemed its a common issue to pop up once in a while. But along with the message, I hear noises from the rear of the car (I haven't moved yet).
I try a few restarts, and the message still appears. Seems to continually pop up while running.
I went to the back to try and figure out where the noise was coming from. I initially assumed it was some solenoids or something in the e-diff. but it turns out its the driver side exhaust valve wigging out. Passenger side seems fine.
https://youtu.be/HjLcQ6RWKcw
Seems very odd that the two issues would appear at exactly the same moment when the car has been running flawlessly up until this point.
No check engine light.
Any ideas?