What are the best diagnostic apps and devices you have experience with? Something that displays graphs and real time info to help give me the proper information for p0420.

Any help would be great. The code reader just isn't enough.

 

i don't use apps but the best laptop based scan tool is from autoenguity.com.
the best code reader is from launch
creader7 or creader123
launchtechusa.com/

 

diagnosing a p0420 involves ruling out the pre and post 02 sensors...ie make sure they are switching normally and no damaged wires, check for exhaust leaks. check and make sure the fuel trim is ok, no misfires...if all that is ok; put a cat on it.

 

I shall do thanks. I keep getting that 420 and 455 codes. Together. I did the gas cap and purge valve but now I am guessing and I realize that. That's why I wanted to get a good diagnostic tools to check the data.