My check engine light came on 2003 dodge dakota quad cab awd engine code p0456

This code is normally caused by a loose gas cap or a bad EGR valve. It is the code for the evap system on your truck. You can go to autozone and they will clear the code for you if you can not do it yourself. You may need to replace the gas cap and or the EGR valve if the code comes back up, these are normally one time things due to the cap not being fully tightened.

There is a small leak somewhere in the emmission evaporative system.
The best way to find it, is to have a smoke test done on it, where they inject smoke into the system, and where ever the smoke comes out, is where the leak is. Most likely a dealer, but call around.