P0420 Code Update and now O/D Light flash

[gtyates]

The CEL popped on while I was driving on the interstate Saturday afternoon. Stayed on entire drive. On Sunday was still on so took to Autozone to get a preliminary reading. P0420 was the only code in the system. On Monday took to my favorite shop and they confirmed the code. They cleared the code, drove truck, hooked back up for diagnostics and everything checks out in spec. Also, catalytic converter temps were where they should be on both sides as well as the converter itself. Nothing is loose inside as there is no rattle. For now they told me to drive it and if code comes back we will deal with it then. No other obvious symptoms are present. Has anyone had this happen, where you get a random P0420 but no problem is actually found? Is this just a strange fluke? Is my '96 Explorer haunting me?? lol!!

 

[apolo607]

maybe my X and your are TWINS...

I am having the same issue, it is the freacking 3rd time that I clear that code.

I have heard that it has something coming from the Ox sensor and/or the catalithic, but I also do not have a good idea of what's going on...

My brother in law (he is a automotive tecnician), told me that there is not any problem and just erase it...

 

[gavin]

I've had that code come and go... multiple times.
I would replace an O2 sensor and clear codes, and the CEL would be off for up to 6 months. So then I would take the "old" O2 and replace another one and clear the code. Sometimes it would come back within a week, so I would clear again, and would be gone for months.
Basically just did that swapping around all 4.

Although it's actually been a year or so since it's been back. *knock on wood*

 

[ncranchero]

Familiar with a little device called a MIL eliminator?

For off road use, obviously.

 

[gtyates]

So I have now driven the truck 3 days and no more CEL. So maybe it was a fluke? Unrelated to the CEL, this morning I got a new light, the O/D light was flashing. Truck seemed to be driving and shifting fine until I got to my kids school and tried to park. Put it in reverse and truck was barely moving and had a jerky feel to it. Not good. But after I went in the school and came back out and started the truck no more 0/D light flashing and the tranny is working normal in all gears. This truck is haunted!