[JDesjarlais]

I got the famous p0420 precat failure code, i havent gotten it checked out yet but even if the pre-cat hasnt failed im gonna get new headers so this car is more reliable. Is this code usually the precat? And does anybody know a good site to get headers from, any you would recommend?

Thanks in advance.

Additional info: 2002 sentra se-r spec v and i live in saskatchewan, canada. so any sites offered would need to either have reasonable shipping costs or be located in canada.

 

[JDesjarlais]

bump. come one guys in need here

 

[Michael48]

I'm from Alberta and i purchased a Megan Racing header from Mosaic Motorsports in California. The price was good for brand new. Unfortunately I couldn't be at my billing address when it was delivered, thus I had to pay another $40 and pick it up at the Calgary airport (UPS store). Tack on customs and the thing gets pricey. Oh well, learning experience I guess...

I should also mention that the damage was already done and my car died about 5 months after the header install anyway.

 

[Black B15]

You should definitely get a header for your car. As Michel48 said the damage may already be done.

I am unsure which is the best option for your car and where is the best place to get it from.

 

[i68k]

before you buy a header, you should do a few things first.
1-read this- http://www.b15sentra.net/forums/showthread.php?t=135241
2-make sure there is no damage from #1 by doing a compression test and leakdown test.
3-if #2 passes, get yourself a catless header and use the anti-fouler method to void you p0420, otherwise you need a new motor or rebuild.

 

[JDesjarlais]

Ended up needing a new engine ($2000, 160,000 kms) and just put on another precat ($950 after install). Im now getting the code again so im replacing the o2 sensors tomorrow because they are both fried at the ends, hopefully this works! Getting headers in about a month anyway so i hope the new precat is still fine...

 

[i68k]

if you did the install, i believe you need to clear the p0420. normally you get a p0420 when your o2 sensors are working properly. if the o2 are the problem, you should fix them, they might richen out the afr and dump the fuel into your new cat, corroding it and damaging it too soon. with a catless header, you foul the lower o2 out of the stream so it lasts even longer. i would get a catless header, and save your precat for your smog test, not sure why you paid soo much for one esp when that seems to be the cause of the motor failure originally.

 

[MurderedSER]

Why would you pay $950 for a new cat AFTER paying $2000 for a new engine, then say you're about to get a header? Why not just save yourself the $950 and put a new header on along with the new motor? Just curious about your reasoning here??

 

[koz]

Ended up needing a new engine ($2000, 160,000 kms) and just put on another precat ($950 after install). Im now getting the code again so im replacing the o2 sensors tomorrow because they are both fried at the ends, hopefully this works! Getting headers in about a month anyway so i hope the new precat is still fine...

How did you know that you needed a new engine? Compression test? Did your car have any symptoms? Rough idling, stalling, misfiring?


I recently got the code but I don't have any symptoms besides lower gas mileage. My mechanic friend thinks its just the 2nd O2 sensor and that I don't need to do any compression tests.

 

[i68k]

most of the time you get a p0420, it is because both o2 sensors are working properly. having this code will richen your afr, reducing gas mileage, and reducing the life or destroying any remaining cats you have. so it will only be a matter of time until you start getting those symptoms. do yourself a favor and get a catless header before your cat corrodes from over saturation. also, you may not need a compression test, but the ceramic will wear the rings, and cause excessive oil burn off, at which point a compression/leakdown test will tell you the validity of the motor. but really, its only a matter of time after precat failure before the motor needs to be rebuilt/replaced, esp if the problem is not resolved.

here's the precat faq:
http://www.b15sentra.net/forums/showthread.php?t=135241

 

[koz]

most of the time you get a p0420, it is because both o2 sensors are working properly. having this code will richen your afr, reducing gas mileage, and reducing the life or destroying any remaining cats you have. so it will only be a matter of time until you start getting those symptoms. do yourself a favor and get a catless header before your cat corrodes from over saturation. also, you may not need a compression test, but the ceramic will wear the rings, and cause excessive oil burn off, at which point a compression/leakdown test will tell you the validity of the motor. but really, its only a matter of time after precat failure before the motor needs to be rebuilt/replaced, esp if the problem is not resolved.

here's the precat faq:
http://www.b15sentra.net/forums/showthread.php?t=135241

I understand all that, but my question is this: how can I tell for sure if the damage is already done without taking off the precat and looking inside? I will get a header if there's no precat damage. But if there is, I'm just gonna let the car die because it's not worth it for me to get a new engine at this point. Will doing a compression test right now tell me i there's damage from the precat?

 

[i68k]

i would recommend removing the precat before the compression test, just so it doesnt suck the ceramic in after youve tested it. if the compression test fails, you can also do a leakdown test. normally from precat failure alone, you dont need a new engine, just a rebuild, replacing the damaged parts that would lose compression like rings, headgasket, etc. if caught early enough, you only need a basic rebuild kit + the rings and other misc bolts/gaskets/sealers. in which case, you could upgrade to 08+ headgasket and headbolts, which are much stronger, some say stronger than arp.