Pre-cat or header options? - code 0420 - Nissan Forums : Nissan Forum
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post #1 of 3 Old 03-28-2017, 02:11 PM Thread Starter
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Pre-cat or header options? - code 0420

I doubt thereís any correlation between the two, but I changed the oil in my 04 Altima 2.5 on Sunday, then yesterday, the car ran fine, but I went to start it back up later that night and had a SES light on. The code I got was a P0420 and looking around, it seems that the pre-catalytic converter is having issues, so, my question is this; whatís a good option for replacing this? I want as little trouble with fitment as possible, donít care about hp gains, etc, just want it to run right for as little as I can spend and still get good quality.

I donít have to thankfully worry about emissions testing here, so if headers are a better options, thatís fine, though Iím honestly a little iffy on fooling the carís computer with a fake O2 sensor reading.


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post #2 of 3 Old 04-11-2017, 06:27 PM
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If you're looking for the cheapest route, just gut the pre-cat. Since you are already getting a code, there's a good chance the pre-cat has already started to break down and will be easy to break up. I just did both of mine on my 3.5 while I was doing a motor swap. One was already broken down and I had it gutted in less than 5 minutes. The other took a couple hours as it was still pretty well in tact.

I used an air hammer with a long bit, a big metal chisel, and a big screwdriver along with my small sledge. The first one just crumbled and fell apart after a few rips with the air hammer (disgusts me to think how much of this got sucked back into the old engine!). I had to beat on the other for a while, separating the insides into 4 smaller chunks that I was able to pull out with vice grips.

If you don't want to see the check engine light, get some spark plug non-foulers from advance auto/auto zone, drill the hole on one of them out to 1/2in and screw the o2 sensor into that end, then connect both to the hole after the precat to space it out.
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post #3 of 3 Old 04-20-2017, 04:33 PM
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Happy to share some header options also!

Pm Sent!

Proudly serving the Nissan Community since 2003 !!
Many QR25DE/VQ35DE Header options & o2 Spacers, intakes and exhaust!
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