[putzee52]

Hello fellow Xrs

I have my 2003 se sitting with 205k miles on it. Just got new tires, tune up and entire timing belt process. Now I have the p0430 code..

Is there a write up for how to change the cat on a 2003? I search relentlessly and cant find anything. Im guessing its a pita and with 205k on the motor probrably a double pita. I want to keep the truck but trying to not pay the dealer $1000.

Also one mechanic told me if I replace one side there is a good chance the other side will throw a code, is there any validity to this?

If there aren't any write ups does anyone have any tips?

Thanks

Jay

 

[clunker]

You are in luck! I will be pulling my exhaust manifolds and primary cats this weekend on a 2004 N/A, and replacing them with some headers. I'll take some notes and pics as I go. You should be aware that some VG33E engines have a single piece exhaust manifold/cat (mine), and others have cats that detach from the manifolds. I took a good look today, and it appears that the most difficult part will be getting that giant chunk of cast iron out of the engine bay. All of the bolts and nuts seem relatively accessible.

My ECU started sending codes for both bank 1 and bank 2 cats within days after I bought it from the PO (or should I say POS). Obviously, the seller cleared the codes before my test drive. My opinion is that if one of your cats fails, then the other isn't far behind. You might as well replace both. I feel the same way about brakes, tires, head/valve-cover gaskets, breasts, or anything else that comes in pairs.

I already was thinking about doing a write-up on the new headers, so I'll just include disassembly information. I'll start taking notes tonight, and you can look for the new thread in the repair section of this forum starting soon.

Cheers!

 

[xnooby63]

Hello fellow Xrs

I have my 2003 se sitting with 205k miles on it. Just got new tires, tune up and entire timing belt process. Now I have the p0430 code..

Is there a write up for how to change the cat on a 2003? I search relentlessly and cant find anything. Im guessing its a pita and with 205k on the motor probrably a double pita. I want to keep the truck but trying to not pay the dealer $1000.

Also one mechanic told me if I replace one side there is a good chance the other side will throw a code, is there any validity to this?

If there aren't any write ups does anyone have any tips?

Thanks

Jay

IMHO and with past O2 sensor headaches... Replace both when it's done especially since you are sitting over 200k

Sent from my XT1565 using Tapatalk

 

[putzee52]

Awesome thanks!

Let me know how it goes. The high mileage on the bolts are scaring me away from the DIY route. Its my daily drivers so I cant F it up. Where you throwing codes as well or just upgrading to headers?

 

[clunker]

I just typed a detailed description of what I found today, and this forum timed me out and erased my entire post. Here's the abbreviated version.

I only got the passenger side done today (mostly because of the headers), but it was easier than I expected. At 200K, your hardware will likely be more difficult to loosen than mine at 140K. I was shocked at how accessible the manifold studs were from the wheel well, and the nuts freed up easily. The driver's side will be much more difficult.

My X has been throwing P0328, P0420, P0430, and P0400 codes since I bought it. Found some vacuum line issues with the EGR today, and I probably solved the P0400 issue. I decided to install headers instead of OEM cats because they should improve mileage and power. I'll deal with the rest of the exhaust later. More info coming tomorrow.

 

[clunker]

I didn't end up doing the driver's side on Sunday because my defoulers did not arrive in time. With the passenger's side reassembled and a drive to work today, everything looks good so far. Next update will not be until Sunday unless anyone has any questions.

 

[putzee52]

Nice job. Did you PB blast all the nuts ahead of time?

Wondering if I should just do all new studs from the mainfold, did they come out all together or did the nuts function properly.


How long did you drive w the p0430 code? Don't want it to go to long.

 

[clunker]

I PB Blasted everything, but the manifold nuts probably did not need it. I wish I had hit the other exhaust flange nuts at least a few more times in the days before trying to loosen them. With a 3-ft. breaker bar and a lot of force, it sounded like a gunshot when they broke free. I forgot to mention that I had valve cover gasket failure on the passenger side, which resulted in quite a bit of oil leaking all over that manifold and it almost killed the starter. That might be why they were so easy to remove. All of the nuts came off except for one where the stud came with it. That nut still freed up easily. The real test will be if the other side is just as easy. Maybe I should pour oil all over it today, so it's ready on Saturday.

The defoulers finally arrived, but one of them had a giant crack in it, so I sent it back. I was planning to replace all of the studs and could not find a set anywhere. In fact, I could not even find information on what size they were. It might be a Nissan dealership-only thing. My studs looked fantastic, but I can't imagine that is the norm. I suspect that this Xterra spent most of its life in a garage because the paint is still gorgeous and the frame doesn't have a spec of rust on it, so maybe it is not a good example of what to expect.

My X started throwing the P0430 and P0420 codes within days after I bought the car in January, 2016. It had almost 130K then and has just over 138K now. You're not supposed to drive with the engine light on for very long, but I figured the cats were already shot before I bought it. What I know now is old lazy O2 sensors can trick the ECU into thinking that the cats have failed, and continuing to drive with an incorrect air/fuel mixture can cause the cats to fail even if there wasn't anything initially wrong with them. If the O2 sensors were the actual culprit, my cats are most certainly toast by now. The seller promised me all the maintenance records, so I could track what still needed to be done. Naturally, he got his cash and disappeared, leaving me guessing. I just ordered some new upstream O2 sensors yesterday because I'm betting that they are responsible for this mess.

 

[clunker]

***Update***

Plan to spend at least twice as long on the driver side as the passenger side. I worked on it for 7 hours today, and I can barely move. Still have at least another 5 hours tomorrow to finish. In addition to all the fun you can have on the passenger side, the driver side has some unfortunate obstacles. The steering shaft has to be removed, sheet metal has to be cut, part of the drive shaft has to be removed, and you have to work around the intake and air conditioning lines. Intake between air filter and throttle body can easily be removed, but I never mess with air conditioning.

I joked about pouring oil over the driver side exhaust manifold, but now I'm serious. I wish I could have parked this thing in a lake of PB Blaster for a few days before starting. Plan on having some sore muscles and bloody knuckles.

You'll be happy to know that I took lots of pics and discovered a few shortcuts along the way. Hopefully, my pain and suffering will enable others to avoid the same fate.