Just did my tuneup, did not do the O2's yet.. but received the dreaded P0420 code tonight.

It is pretty cold out, I noticed my temp did not get up to true middle (whatever temp that is) and a couple times have smelled a funky exhaust type smell but attributed it to other vehicles around when I smelled it. It being a couple times only, not a consistent exhaust smell (so fits other vehicle's nasty exhaust smell).

Anyway. I am going to go get new O2's and install them tomorrow. I have been using Lucus fuel additive so not sure if I funked up the O2's or the cat possibly?

I know by the condition of everything else the O2's need replaced. Will be doing that first thing in the morning. After buying the truck I decided to pick up the 5-book manual from Dodge. The information is attached for the P0420 out of the manual.

 

damn. Any way to rotate the pictures?

EDIT: nevermind, did it on comp then reluploaded them.

Anyone have any success stories on getting the P0420 code to go away?

 

I have heard not to use Bosche plugs. Correct? Only OEM? How about NGK (NTK)?

 

I would replace o2 sensors first. Bad or malfunctioning sensor can cause cat codes.

 

I think it was the Lucus Fuel Cleaner personally. I think it fowled up the O2's. They are more than likely really old if not factory so I figure I would get them anyway. I need to burn a bunch of this fuel off. Didn't know we were getting snow first thing, so I am going to go to a buddy's right now and change them out.

 

From what I heard it isn't as much a cleaner as a "lubricant".. so I think it goes through largely unburnt. I am sure it coated the crap out of the O2's.

 

This did get me to going through what I want to do for exhaust. I still don't know how many cats or where they are at. I will find out shortly. I have a plan.

Anyone know which "Y" pipe we use? Do the 4.7 fit the 5.9? How does that work anyway? I see a lot of interchangeable parts that I would have thought would not interchange.. but on exhaust I see a lot of the interchanging but not sure if it is just a "site error" for the vendor sites or what..

 

after new gas the MIL light has gone off. I am positive it was the Lucus Fuel Cleaner that fowled up my O2's. I won't be using Lucus again, or if I do way below what they say to use.

I am going to get a few more tank fulls of gas and reset the trouble codes and then I will see what happens. I don't think my cat is bad at all. And don't trust the parts people about the P0420 code being a bad cat. They could honestly care less what it is, and yes most times it is an O2 code and NOT the cat being bad (code).

Will update later.

 

I am dealing with the same issue on my 2007 Range Rover. It will turn on/off randomly. I Think the CAT needs replacement. Until I am sure, I will continue to search.

 

I went back to the parts store tonight, returning some brake shoe cores and borrowed the code reader.

From the time I made this thread till now I had a P0380 code also which was misfire in #2 cylinder. I just replaced wires and plugs and cap/rotor and coil. I think the lucus fuel injector cleaner screwed things up pretty good. I am going to replace the 02's on friday and will see what that does. I erased the codes tonight, drove it around for a bit and the MIL never came on again. I am thinking the Lucus fouled up the 02's or possibly cleaned out something that fouled up the 02's and then checking the misfire code.. it also states that a bad 02 or (all the parts I swapped out already) or bad cat can be the cause. I honestly don't believe it is a bad cat. I think it is the poor upkeep of the truck by the previous owners and me running cleaner through it that has funked things up.

I will let you know what I find out, but I would rather spend money on a new 02's and have piece of mind that way, then to go and replace the cat and have it still acting wonky and need to replace the 02's afterward anyway. I am working on a process of elimination with less $ first.. first then move up to the expensive stuff. I won't just replace the cats. I will redo the whole damn exhaust before spending what they want on a factory cat. I can get way better with aftermarket cats and for way cheaper.. and to have a higher flowing exhaust to boot.. hey now!

Just the way I do things. Good luck with your code and all. Let me know what you end up finding out, post up what you come up with!