i have a 2003 ram 1500 with the hemi and i had to replace my cross over pipe cause it rotted out. i took it in and ended up haveing a whole new system put on new cat, gibbson stanless cat back, everything. when i got my truck back it ran like **** so i replaced the front O2 (my truck only has 2 O2 sensors for some reason and headers came like that when i bought it) from the after market to a mopar and it fixed the idle problem. i jusst recently replaced the back O2 with a mopar and i am still getting the code P0420. i changed the O2 sensor yesterday and drove about 25 miles and no code, i drove to work today and it threw the code. in NY if i cant get this fixed then i can not pass inspection cause they hook a computer up to my truck to check the monitors. what can i do besides sell the truck LOL.

 

My 05 Ram was throwing the P0420 code too. I put an O2 extender on the back driver side O2 sensor Sunday. I had cleared the code the day before, and 20 miles after installing the extender it threw the code again. I cleared it again, and have driven 75 miles with no code.

 

i cleared the computer this morning after i pulled over, pulled out the handy dandy obd computer i bought and has paid for its self many times over, and cleared it. i hope that i can get this thing to sneak threw inspection cause i am deploying to iraq soon and my fiancee will be driveing my truck when the weather is bad.

 

ok i drove around for like 25 miles and no light so i went down to my friend at the shop to have a inspection done. 4 out of 5 of my monitors are working so it passed. the evap monitor hasn't cycled yet but when i hit around 70-100 miles it should cycle and be ok. im good for another year so i at least have a truck when i get back from iraq and my fiancee has something to drive in the bad weather while im gone. i was told by the shop that you should only use mopar sensors cause the after market ones are not made the same, they can fit multiple vehicles, and another thing i learned was NEVER and i mean NEVER take anything to monroe muffler to have exaughst work done. they billed me for mopar sensors and put aftermarket in it. the O2 sensors that came out dont even look like to ones that the dealer gave me, but long story short i think its fixed and it passed inspection.

 

ok got it through inspection and then on the way home from work, didn't even make it 4 miles, and bam the light came back on. same code P0420 catylist below efficientcy. it seems like since i fixed monroe mufflers mess up by putting mopar O2 sensors back in it that i make it farther before the light trips. does anyone have any ideas to get this issue fixed for good cause i am all out of ideas.

 

sounds like u need to do that trick with the 02 sensors. i've never done it so im not sure exactly how but it involves wrapping them in something and putting them into the exaust like that so it wont throw a code.

 

i would love to know what trick you are talking about. i will look around to see if i can find what you are talking about. i hope that someone out there knows what the above post is talking about cause if i can not resolve this problem im going to trade the already paid for truck in and let it be the dealerships problem. because of this truck throwing this code all the time i am forced to drive my VW jetta allot more and believe me i dont like that i am 6'3" cramed into a 100hp mini car when i am use to driving the 470hp ram with all the leg room i can handle. lol

 

ok i talked to a dodge mechanic at the dealership, he says that i did everything that they would normally check when this code happens. the only thing left or i guess the next step is put a OEM mopar CAT back on it or flash the computer. he said that if monroe muffler sold me a cat that didn't work as good as the factory one then the code would happen. i am still trying to figure out why i have only 1 cat when the dealership diagram shows 3 cats, one off of each manifold and one big one after the crossover pipe. i only have the one big one.

 

My truck threw the code again today, so the O2 extender didn't work after all.