My Power Programmer for my truck tells me that I have a DTC code of P0420. I believe it has something to with the catalyst efficiency being below threshold. Do I get a dealership to fix this crap, or can I get the tools and materials to do it myself?

I believe that code is your o2 sensor,might want to look code up,and sometimes codes sends u to the area of something else that needs replaceing,might want to get a second look at it before replaceing parts save u some money

The ECM in your truck receives inputs from an oxygen sensor in front of and behind each converter. The converter processes and reduces exhaust emissions. The ECM knows there will be a difference in information being reported from the front and rear oxygen sensors, as the converter processes exhaust emissions. As a converter ages, it becomes less efficient. This loss of efficiency is known by the ECM, because of information that the oxygen sensors, mounted before and after the converter, report. A P0420 converter efficiency code doesn't always mean the converter needs to be replaced. A defective oxygen sensor can also cause this code to be set by the ECM. Check the oxygen sensors, to be sure that they and other related systems are operating properly. If everything checks out, install a new converter.