took my 2017 to the dealer 3 times with those errors all to no help. Took it to another dealer who took the manifold off and found the broken link for the runner inside the manifold.
Jumping in here :)
I purchased a 2018 GT350 last year to be my daily driver - and I have zero regrets. I was the second owner and it only had 4300 miles. It now has 9000 in about 6 months. I live in the Seattle area. I use the stock tires for summer and have a set of Michelin 4S for the winter...