So i have an 05 hemi with a stock exhaust for now and a CAI. Today on the way home it through the P0420 code. The truck has 37,000 miles. Me being the second owner, not for sure if the plugs have been changed prior to me owning it. I've red on here about the code, 1/1 catalytic conv. eff. What would you guys suggest? Have the dealer scan it to see if it is an O2 sensor and if so which one? Push them towards replacing the cat? I'm kinda at a stand-still as of now. Guess i could get under the truck and hit the cats to see if they rattle. That was one of the things to do i red. Any help would be great!

 

So i'm thinking about changing the plugs to see if maybe that helps........couldn't hurt anything i don't guess

 

You are on the right track with checking the cat to see if its damaged. Check for any exhaust leaks around the area of the cat.

Also I read that if you have recently replaced a rear 02 but have an aging front 02 then the code can be thrown. I would replace the 02 sensors before springing for a new cat.

I don't think that changing the plugs will fix the problem, but it would keep the truck tuned up.

Good Luck

 

Cats seemed to be good. Put some Champion double platinums in it and drove it all day sunday and today and no light! I talked to a veteran mechanic at the dodge dealership this evening about the code and he explained it kinda like this.......lets say you have a plug not working up to it's full potential, you get somewhat raw fuel passed on through the exhaust, through the cats and the back sensor read enough different to set a CEL off. All i can say is he light is off!! woo hoo!!!

 

nice, least you got it fixed.

 

Just hope it doesnt come back on...........LOL

 

Damnit weed!! lol The last post i put on here....well, that night, the light came back on. Got a P0133 this time. Swung by the dealer the very next day for a $45 scan and he said it was the O2 before the cat on the driver side. I told him i'd be replacing it and he gave me this spill about using the mopar sensor or it'll go out again soon, so at $50 i went ahead and bought it, put it in and reset the light. While i was at the dealership he said i probably would want to put the original airbox back on because aftermarket CAI's tend to set the O2's off. Don't really understand that being since MOPAR themselves make one. Anyways, after driving with the new sensor on for roughly 100 miles, i again tripped the Po420 code again. I mean could this be the cat going bad hopefully! the only reason i took it in to have it scanned was so he could tell me exactly what sensor was bad. I'm sorta lost here but the $45 scans are already getting old and i've only had one. Thanks for hearing me moan and groan.

 

Take it to the dealer and don't let them give you no **** about replacing the cat. They are under a federal 8yr 80k mile warranty and a p0420 means most likely you have one going bad. It's monitored by 02 inversions and if #2 sensor shows a certain amount of activity compared to #1 the pcm tells you the cat has lost efficiency.

 

Going in the morning to so. Reset the light lastnight late and drove it this morning just to double check and sure enough the P0420 came up again. I hope this isn't an ongoing issue. That would suck...

 

As always, let us know what happens