Thanks JFloors. I'll give it a try. Seems like a pretty weird sequence. Who does that in real life? Seems like I've done enough driving, especially on the highways to have accomplished monitoring everything...

 

Didn't have a chance to go thru the process suggested to clear the drive cycle. My son took the truck on another one of those 120 mile round trips and when he came back, all monitors were ok no codes present.

Got to say, the non-fouler trick worked. Been getting that P0420 code for quite a while now and this is the first time it hasn't come back. Truck has over 250K miles on it and I'm just not willing to put a bunch of money into it at this point.

Just for clarification, in case anyone wants to try this, I started with putting one non fouler on with some steel wool. The non fouler was drilled all the way thru. This did not work. Code came right back. Put 2 non foulers on with steel wool stuffed in there and code has not come back yet. Lets hope it stays that way for a while!!