My truck has headman headers and a custom CAT exhaust. This P0420 Code ( O2 sensor crap) keeps poping up. The headers are ceramic coated so my truck is running cooler than normal and the O2 sensor is use to reading a higher temp (so i have been told). It doesnt affect my performance at all and my superchips tuner will only keep it off for about a day and then it pops up again. I could just leave it on but I hate the MIL light being on all the time. ....Suggestions Please

 

SC is going to get rid of P0420 until you fix the problem. If you dont fix the issue, the CEL and code are going to keep coming back.

P0420 has to do with rear O2 (right side I think) cat deficiency. It is saying there is no difference between the front O2 and the rear O2 and therefore it thinks the cat is not working. It could also be because of an air leak in the gaskets at the headers or even in the pipe where it was welding.

It has nothing to do with exhaust temps.

I used to get both P0340 and P0420 but that was because I removed my cats completely.

Unless you are custom tuned (which I dont see) you will need to check your headers and welds. If those are ok then I would add non-foulers with 0000 steel wool and put them on the rear O2's. They will only cost you $10 for a pair of two. If thats not it then it is time to replace the rear O2's and those are about $25 each.

In this link Hammer does not show the steel wool but go buy some 0000 steel wool and take the first non-fouler that isnt drilled out and pack as much steel wool in it as you can. Then screw the drilled non-fouler into it and then the O2. Do this on both sides.

Then reset the CEL with SC and reset the PCM (pull the fuse)

https://dodgeforum.com/forum/3rd-gen...ving-cats.html

 

thanks ima try that

 

Yea I checked the headers and exhaust near the cats, everything was good, no leaks. I have some 02 simulators that went on my old f-150 and I looked under there they each have the same number of wires just different connections. Wonder if fabing something using those 02 sensors mite work. If not then I have to try that steel wool trick. I was told by a friend that if I take it to a tune shop they can plug in w a lap top and turn the 02 sensetivity way down.

 

I've found that the non-foulers by themselves work about 75% of the time, when they don't then adding the steel wool inside the non-foulers usually does the trick.

A rear O2 does NOT impede performance at all, no changes are made by the PCM other than triggering a CEL. Now if it were the front O2, the PCM will make changes to the A/F ratio in an attempt to find the right ratio and will usually make the truck run worse and use more gas. So in your case, it's only a matter of having an annoying CEL on.

 

Let us know how that works out for you.

 

.I checked that non fouler link and seems pretty simple, imma try that first then

 

Just remember afterwards to reset the CEL and reset the PCM. Then later report back on how it is working for you.