Read this.

 

Thanks Hey, hopefully that will help out

 

Clear it and see how long it takes to come back.

 

I see that on a copied list from somewhere else, but then why do we all shim the rear sensor then for a p0420? I know you have done the non fouler trick and so have I for the same code. If there really is a 1/1 designation (which is hard to find outside the faq list), then I think HeyYou hit the nail on the head that it must be cat 1/1 since the code is for the cat. But either way, the rear o2 sensor is the one that checks the pre vs. post values thus checking the cat. Let me ask this, do pre 94-95 vehicles with no rear o2 throw a p0420 with gutted cat?

 

No, they don't. They don't care about catalyst efficiency, and they don't monitor it. Code structure for OBDI is also different.

 

I did clear it and one time it took 3-4 weeks before coming back on and another time 2 weeks.

 

I thought about that part after I posted it. touche

 

All I'm saying is that 1/1 means what it means. Maybe the FAQ description is wrong, I don't know. And btw, when I had a problem and had to use the nonfouler's, I was getting a P0430 or P0432 code, I forget which at the moment.

 

I think the 1/1 is just an 'interpretation' here. The 'generic' description is: Catalyst System Efficiency Below Threshold (Bank 1) So, in this case, I think the 1/1 designates bank one, cat one. For those with california emissions..... there are a selection more codes for the other cat.

 

https://dodgeforum.com/forum/2nd-gen...hflow-wtf.html

In post 5 you confirm the same problem of throwing a p0420 and suggest using non foulers
In post 20 you again push the non foulers for my p0420 problem.
In post 24 you again push the non foulers for my p0420 problem.

I did eventually throw p0420 with the new cat after 6-8 months, and did the non fouler trick. I was more worried about PA visual inspection which is why I pushed to replace the cat in the first place.