You may have seen my thread on the SES, TCC OFF, and SLIP lights on....I got that fixed with a new coil on 6 and new spark plugs.

Now after a day of driving the SES light came on, I check codes and have a 505 and a 420. These codes were not even pending before fixing the other problem. A couple things to note, When I was replacing plugs i noticed a vacuum line off above the TB so I replaced it. Also Plug number one was binding trying to get it out, so I had to work it in and out a while to ovoid stripping the head, I sprayed some penetrating oil in there to assist. I cleared the codes when I got home and drove it tonight to take the kiddo candy collecting, plus some running around. The SES light has not come back yet after probably six or so start/stops, but I expect it will at some point. Any Ideas ? Could it have just been a fluke from connecting that Vacuum line that had been off for who knows how long ? Could penetrating oil have triggered the catalyst code ?

 

Possibly to those thoughts. I would suggest you look through the FSM, specifically the EC section. It will give you thinks to look and check for both codes.

http://boredmder.com/FSMs/Nissan/Maxima/

 

I have the FSM downloaded already, I will give that a shot. And as suspecter the SES light came back on this morning.

 

Was is the P0505 or P0420 that returned?

P0505 may have been fixed by you fixing the vacuum hose.

The P0420 is you bank 1 cat. I will just say emissions suck big time. If your max has a lot of miles you can be sure the cat would needs replacing. However, if you are interested in exhaust modifications now would be the time to do some searching. If you don't want to mod your exhaust and aren't in cali they replacing the cat will not be too expensive($220-$350 just for the part depend on brand).

 

I have not checked the codes yet again. What exhaust options do I have (cheap) I am in an area with no emissions testing

 

^^^^ your cheapest option will be to replace with aftermarket cat and be done with it. If your looking to go y-pipe then its time to search for the options you will have. I have a no emissions county either but this is my dd and I will keep her stock mechanically(besides a AEM drop in dryflow filter). I have cali emissions and I have had to replace both banks cats, but my exhaust and O2's are good now lol.

If these cats fail, I will be getting rid of 2 or the 3 cats.

 

Well...to clarify what BigLou is saying. You have 2 pre-cats and one main cat.

The y-pipe only replaces the rear pre-cat (bank 2). A P0420 engine code is for the front (bank 1) pre-cat. The only mod to remove the bank 1 pre-cat is to install headers. There are options in this area, but they are not necessarily cheap.

As BigLou said the cheapest option is probably replacing the front (bank 1) pre-cat and be done with that.

Of course...that is if the SES light is P0420. Go get it checked to see the code(s) so you can determine what to do next.

 

if you have no emmision testing, I would add a fouler plug (o2 spacer) to get rid of that code. Should be under $10 for the part. This is only if your car is running fine.

More than likely though, your cat is clugged due to your misfire problem (you mentioned you had a code for cylinder 6). If cat is clogged, eventually it will cause some serious drivability problems, In that case, the cheapest route would be to gut the cat and instal the fouler plug as mentioned above.

 

What is, and where do I get the fowler plug ? Is the front cat just a bolted on part, or is it welded in ? Can I unbolt it, gut it and replace it easily ?

 

But if he puts on a ypipe he can just gut the front cat before installing the Y. It's the front manifold, it will be easy to remove.
And then gut the rear. F cats.

Doing anything else (aside from headers or gutting the stock Y) is a waste of time and money. Cheating to get the code off will just land you a ruined engine in the near future.

 

I dont want to cause any future engine problems, it runs great right now ! Is there a good site to go to for these parts ?


Just a quick search I see some Y-pipes that take out both cast, as well as the one that only replaces the rear. Around $300 on Ebay....Any good ?

 

I would say to unbolt the front of your main cat and look in there first. I know everyone says p0420 is always the pre cat and maybe I am the only one that it was the main one. You can get a new gasket for like $4, its worth a look, I spent $200 on a ypipe and ended up not needing it because everyone said it had to be the pre cat, then had to search around for a solution for the main cat. Trust me just take a look.

 

What would I be looking for ?

 

Broken pieces sitting in there or if its clogged up at all. On mine there is a metal mesh that surrounds the catalyst on the walls and it had come loose and was blocking flow.