Gives me a code po 449 evap.vent emission control what is this?

DTC P0449 - Evaporative Emission Control System Vent Valve/ Solenoid Circuit Malfunction
The most likely problem is the evap vent solenoid which is mounted under the truck back by the fuel tank. The code is related to the circuit to the solenoid. Most likely the solenoid is shorted or Open which is causing the code to set. The other things to check if the solenoid is not the problem is the wiring to the solenoid could be corroded or broken or damaged. The last thing to suspect is the pcm which is the computer that runs the system. It could have a faulty driver inside, but I would suspect the solenoid or wiring first.

There is a bulletin for the vent solenoids getting dirt or road debris inside of them so when you go to get your solenoid, you may get a kit that will require you to relocate the solenoid and add a section of heater hose and a new inlet which you will need to mount around the passenger side of the trans. This keeps road debris and dirt from getting into the solenoid.

Check Diagnostis Information Procedure.

Hope this helps and just keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa.