New member bringing post back from the dead. Just turned 99000 miles on my 2015 tuned SS and had to limp home with a P0300 code. Towed to the dealer and found out it was a broken valve spring. Good news is there was no further damage but wanted to say thanks for the info here as I knew to shut down as soon as it was safe and check code before proceeding. I keep my Livernois unit with me just in case for times like this.