My car just got this same issue. After minuets of driving on the hwy the CEL came on. I just came from the dealership last week for the Slave Cylinder. And now a damn CEL....

Car has 2970 miles.

If you had a slave cylinder issue, then you should have a 6MT. The reflash for the temp sensor is for the 7AT trans. Also the OP has the AWD G37x. If there is a G37x coupe with the 6MT, I'm all in........