Catalytic Converter Failure P0420 =--> Header Upgrade Time!

[MAJ_Jimbo]

Apollos2: Thanks for the great write up on the CAT situation. My SES light came on a week and a half ago. I took it to the dealership, and they confirmed a PO/420 code. A couple of hours later they said they couldn't confirm anything, and so the SES code was cleared. It went on again 2 days ago, took it in, and PO/420 code again.

Prior to going there I read your thread so I had a little more information prior to arriving letting them know that I think it's bank one CAT. Sure enough, and this time they didn't argue, it was. They said that a line graph on the CAT pattern was the same for front and rear O2, but the technician went ahead and dropped the lower pipe to find bank one CAT damaged.

I was at 47,995 on this issue. Premature in my opinion as I have never dealt with a car with the low of mileage having any CAT issues.

Either case, thanks for the great write up...came in handy!

Jimbo

Originally Posted by Apollos2

As many of you may or may not know our cars are prone to Catalytic Converter Failure.
Our cars have three catalytic converters. One in the Y-Pipe, I've never heard of this one failing. Your can WILL pass emissions test with out it. (It may not pass a visual though, depending on how you may have eliminated it). I know a guy who bored his out even though I've heard we have very efficient cats in the Y-Pipe, it didn't make his car faster but he was still able to pass emissions. Visual and exhaust. Lesson: don't waste your time eliminating that cat.

We also have two catalytic converters at the back of the engine compartment. I believe they mount to the bottom of the exhaust manifolds. These are the ones that can fail. They can melt, restricting flow, and/or eventually start to break apart. If they start to break apart, the particals can potentially get sucked back into the engine: failure.

If one of the two pre-cats start to fail you should get a
Service Engine Soon light. You can always go to Autozone and they will pull the code for free.

Pre-cat failure codes:
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
P0430 - Catalyst System Efficiency Below Threshold (Bank 2)

I believe these pre-cats are covered under the emissions warranty which goes until 80,000miles. All of the failures I know about occured before 80k.

My Service Engine Soon light came on yesterday. I went to Autozone and pulled code: P0420 - Catalyst System Efficiency Below Threshold (Bank 1).

I'm at 80,200 miles. I could go back and ask Nissan them to cover it under good will or something like that. Not sure if it would work to well. They already fixed my AC that way.

MSRP on the right cat = $757
MSRP on the left cat = $550

Headers = under $700


So I have opted to go the header route and not have to worry about it. I called Brian (Cattman) placed my order. 1 set headers, 1 cat to weld into my existing Cattman Y-pipe. ETA 4 weeks

I'm not to sure what I will do with the car until then. I hate to drive it around and risk jacking the engine.

Here are a couple of other threads on the topic:
http://www.6thgenmaxima.org/forums/v...hlight=clogged
http://www.6thgenmaxima.org/forums/v...hlight=clogged

[Apollos2]

Your welcome......I agree 47k is really early but hey at least you got it replace on their dime. Did they say anything about Bank2? I guess just watch for more codes.

[MAJ_Jimbo]

Apollo: No info on bank 2 - I guess I should have asked that. Car only has one year left on extended, but some time on the CAT/emission. I really don't mess with the SES...when it comes on, which has only been twice since I've owned the car, I take it to the dealership since it's under full warranty. They have been pretty good at stuff. They even noticed when checking my gas cap today that the little plastic strap was broken and replaced it - apparently not under warranty, then again, not more than a 2 dollar part in the normal world...

Jimbo

Originally Posted by Apollos2

Your welcome......I agree 47k is really early but hey at least you got it replace on their dime. Did they say anything about Bank2? I guess just watch for more codes.

[Kanadian]

Hi everybody (this is my 1st post)
I have an 06 Maxima. The SES light came on at 36,045 (how ironic). Drove it till 38,400. The P0420 was the diagnosis. The dealership changed the catalytic converter for free (emission warranty). I am not happy to have that king of problem at that low mileage. Anyway, I see that Apollos2 recommended engine flush. Now on other parts of the forum posts are very cautious about that since the car has little miles and the flush kind of have a strong solvent . I have been smelling synthetic smell from the engine lately and at the last oil change the mechanic said that the oil was too dirty (and a bit burnt) and recommended an engine flush. Any thoughts on that? Your help is appreciated.
Al

[Apollos2]

Did I recommend an "engine flush"? Perhaps tranny fluid change but if your oil is dirty, you should get it changed.