2005 xterra. 96k miles. Heard I could just remove cats and bolt back up or bypass cats with some kind of spark plug adapter or hollow them out and re-install shells...idk. I am concerned about what else may happen if I start jerry rigging stuff. Any solid advice would be appreciated greatly. Im a disabled vet on a small disability income. $3k is alot for me. We live in oregon if that helps with advice.

Welcome aboard!

First question: Do you have emissions testing where you live? If not, keep driving it. Seems low mileage for the cats to be shot.

Don't hollow them out. There's all kinds of bad stuff in a catcon (bad for you and bad for the environment).
You can purchase a full replacement set for $300: https://www.ebay.com/itm/Fits-2005-2011 ... 2682983977
O2 sensors are inexpensive as well: https://www.ebay.com/i/273463193786

Installation is simple, we'll be here to help. Thank you for your service.

AZhitman I salute you Sir and in return thank YOU for your service via your reply. You (and people like you) are most certainly welcome for mine and despite what happened to me, I am honored to have served you and all the other well meaning "good" people of our country (not the bad politicians or corporate S.O.B.s). No, I don't have emissions testing in Oregon. I understand and agree with your recommendation to NOT hollow them out for the purposes of human and environmental toxicity. We must all do our part to safeguard our planet in whatever ways we can large or small (not preaching, just been watching alot of Netflix documentaries). I will purchase the replacement parts you mentioned and sincerely thank you for your candor and "can do" attitude. Thank you.

Is the check engine on? If so, what are the codes. If you are getting P0420 and P0430 codes, then you could try a spark plug anti-fouler in between the O2 sensor and exhaust. You basically remove the O2 sensor, screw in the anti-fouler (the threads are the same), then screw the O2 sensor into the anti-fouler. Do this on the rear O2 sensors, downstream from the cats. The anti-fouler simply removes the O2 sensor away from direct exhaust flow and gives it time to provide a reading. Now, I haven't done this on my FX50, but I did use them on my FJ Cruiser and they worked perfectly.

^ All correct.

Hello Dennis! Thank you for your reply. I can't believe how knowledgeable, amazing and helpful people are on this forum. I humbly thank you and of course AZHitman for his reply too. In answer to your Q & A, No, the Check Engine Light is NOT on right now. It did come on a few times over the past year and each time it did, I erased it with my scan tool. However, it is NOT currently on. When I did check the codes, I got P0420, but when the local Nissan dealership's service techs checked the codes yesterday, THEY got both P0420 and P0430 and charged me $117. Their invoice literally states "Found code P0420 and P0430, monitored both front and rear sensors, front acting normal, rear both showed evidence of cats not functioning". They of course recommend replacing both cats and both rear 02 sensors...very expensively. AZHitman gave me an awesome and very specific option to consider on ebay and I have been perusing the offerings...very impressive.

Now the spark plug anti-fouler is another brilliant idea. I believe that would be the least expensive option (aside from doing nothing), but I am concerned as to what that would "do" to my engine or what negative impact that would have. Seems to me, the cats could still continue to melt internally or plug up (or whatever) and that may cause even more damage down the road. Perhaps that would even cause my engines computer to misread data and totally throw off my air fuel mixture or cause lousy performance...I'm not sure. I don't understand how the cat system actually works or if by "tricking it" with an anti-fouler hack, what the negative repercussions would be. Could that back things up and blow up my engine or cause worse fuel economy or some other disaster? Would that darn check or service engine light keep coming back on? Hmmm.

I know the dealer says "replace with OEM and pay for it". That's what they're supposed to say, because they're like big pharma. I can't afford that, so I'm deciding between ebay parts and your anti-fouler idea. Both are excellent suggestions and highly appreciated by me (and hopefully many others on this stand straight, head up, chest out forum). What would you do if you had the choice between ebay parts or the anti-fouler? Do you see a "best" option? I know it's up to me, but input from honorable souls is always welcome and appreciated.

Quick answer: The O2 extenders won't hurt a thing (although, they can be a pain to modify AND to get fitted just right).

A catcon simply catalyzes unburnt fuel and byproducts of combustion (burns it) before it exits into the atmosphere. Nothing magical.

At 96k miles, I'm sure the dealer is full of crap. Cats last FAR longer than that (I've seen MANY with 300k+ miles), and when they fail, the code comes back instantly... nothing that will damage the engine.

P0420 and P0430 codes CAN have other causes (a stuck injector, a bad plug, dirty MAF, a vacuum leak, even a cracked manifold).

If it were my vehicle, in your situation, I'd do the following:

1) Nothing. Drive it. If it's running smooth and you're not seeing other symptoms, roll on.
2) Order the O2 extenders and fit them (know that they *may* not work, but in most cases they do).
3) Replace O2s (non-dealer parts).

96k miles - She's just getting broken in. Our 05 Frontier (same drivetrain) was bulletproof for 150k brutal, abusive miles.

Watch this video for the non-fouler (anti-fouler) info. I had forgotten about drilling the end out. They should run you less than $10 at any auto parts store. You will need to know the size of the O2 sensor to get the correct non-fouler size. Probably 18 mm.

https://www.youtube.com/watch?v=uZ4j2h4-9_k

Outstanding AZH & DMG! I believe your inputs are above reproach, sound, reasonable and highly economical. Talk about potentially solving the problem at the lowest possible level with the least amount of cost, I believe you've both highly enlightened me and have shown me how to do that. I understand that it may or may not work, but trying the anti foulers first IS worth the attempt. That was a good video Denis. Can't believe that guys catcon was mentioned to cost "just" $200. (obviously NOT from a stealership. Anyway, in all likelihood, that tactic may improve my situation too and I can always spend more and go up from there (gulp). But of course, solving problems and saving money is my first objective by necessity. I also acknowledge through your generous inputs that there could also be other contributing factors to the vehicles disposition and if that is the case, I'd be even more financially screwed, so starting at the simplest thing first seems the most prudent. I think I've got it from here. I do not know how to thank you AZHitman and DenisMcG, but picture me standing up and rendering a crisp salute and a BIG HooAah! to you both because THAT is what I just did with great pride, honor and humility. You both have given me solid confidence to tackle this and are worthy of the Humanitarian Service Medal in my book. Thank you men.

I did it! Thank you AZ Hitman & Denis McG! Ended up buying four 02 sensors and two cats from ebay. They were not anywhere near as quality as factory oem, but the total price was less than replacing ONE 02 sensor at the damn dealerstealership. It took me two days to do it, but with a LOT of patience, wiggling, thinking, a bunch of swearing and taking breathers to keep "things" in perspective, I got everything in and the damn Xterra runs great. Looking back, I am WAY more pleased to have replaced everything myself as opposed to jerry rigging stuff or feeling raped by the dealer. It was tough getting the original flange bolts and nuts out. I didn't realize I needed a "inverted star bit" (bought it at my local auto parts store) to back of those bolts after cracking the nuts, but not a big deal. Only VERY minor leaks after install around the triangular flanges after install (due to not an exactly precise factory fit despite ebay description), but I fixed that with some muffler weld putty from the local parts store too. After install I cleared the code and it never came back. Totally worth it. My Wife thinks I'm a stud. The way I see it, I earned (saved) THOUSANDS of dollars with just a couple days effort and your guys's advice. Thank you again Sirs. Happy holidays.

Good stuff, I just had to do all the ignition coils and spark plugs at 95k on my 2005 and I am cringing about this work. have you done those yet, I unfortunately left my car at my mechanic who didn't tell me he was spending $900 bucks on the those coils, they are 50% cheaper on Rockauto.......if my cats fail I am going with this vs. factory.

Ironically BadQ45t, just before I did my cats and 02's (in my long post and with AZ's and DenisMcG's input), I personally replaced my coils, plugs, valve covers (had oil in my plug wells) and manifold gasket (to spec from this forum's available spec sheets). That was a breeze compared to my struggles with the damn cats. The O2 sensors were easy if you have an 02 sensor socket or better yet - claw. I think the only "non-problematic" option to cats is having someone else do it, but to me, that cost is problematic. Of course, that spark arrestor hack is also an option (previously posted). Anyway, I soaked the cat bolts with PB Blast the day before and again the day of replacement. That made working with those original cat bolts much easier. I also needed a size "E-10" (External Torx Socket) for those bolts because they're some kind of weird double locking bolt. They have a regular nut you need to crack and that external torx head to back them out. Take your time and don't stress. You CAN do it yourself with ample time and alot of patience. When it comes to the heat shield covering the drivers side cat bolts, carefully remove the three bolts that hold it in so you don't lose them and slide/jimmy/wiggle the shield toward the front end and a bit upward just enough to gain access to those cat bolts. I took the tires off to do the cats and did it all on my sloping driveway on jack stands and wheel chocks. Not the best scenario, but after I did it, I gained a HUGE amount of confidence and saved thousands of dollars. Everything still works great to this day with no problems. It's NOT a fast job (not for me anyway...maybe others), but it can be done with the right attitude, aptitude and tools. The replacement cats came with regular nuts and bolts. I lock tighted those after I was satisfied with the leak checks and torques. Guess it's all just a question of time versus money. After ALL that work, my visual inspection of the old cats looked like they really did need replacing, so maybe I could have gotten away with just 02's. Idk. I just freaked out when the Stealership wanted soooo much money and they said it was the cats, so I went ahead and did the whole darn thing. Not sure if any of this helps you, but that is my intent and attempt to give back to this forum what little I can for those (previously mentioned) who came to my aid like true heroes when I needed it.

^ THIS made my day.

Nice work, sir. Hope you stick around - you're definitely our kind of people!

Right OEM cats are way expensive, seems like there are some cars with no options to get aftermarket ones and others you cannot find a darn thing out there. Thankfully we can get them, I have zero mechanical ability and no time to spend on it, thankfully I have the funds to pay others. I will take this to muffler shop instead of local mechanic, they are much better at dealing with this stuff and way cheaper.
My brother had a Lexus LS400 that he finally junked when he had to replace 4 cats (2 pre and 2 back) with estimate of $3000 and that was 5 years ago.