P128a cylinder head temp sensor
 

Advance ran the code for me but the code reader says "no definition, see manual". Has anyone ran in to this code. The engine light just came on 2 days ago and I don't have any problems with my truck as far as I can hear or feel and my gauges are where there suppose to be

Sounds like the Cylinder head temp sensor is going. I have mine sitting on my work bench. it's on the passanger side head under the intake manifold. https://cimg2.ibsrv.net/gimg/www.f15...b452b36665.jpg

Cylinder head temp sensor