2014 Prostar Maxforce 13

Check engine light came on just bought this drove only hour or so and sat for 3 moths ready to go now and don't know what light is on for. Have a Nexas 102P code reader that I bought because it says it can do a force regen on this engine and I hooked up to see what the Check eng code was for and it said there was a communication error and to make sure this vehicle was obd2 compliant.
Tried the trick or pushing the two buttons on steering wheel cruise and dash says" diagnostic codes are not available from ECG" Any help besides take to a dealer?

 

Not very helpful but I guess you didn't say take it to a dealer.

 

I am having them take off Speed limiter and now password if I can, anything else you would do? this is my first truck not sure what I should be thinking about.

 

Took it to Int. They wouldn't set so I could see codes just told me "those codes wouldn't help me without their sophisticated diagnostic tool" who cares it put me somewhere in the right direction.