[acespecv]

pre-cat prob, not sure how to exstend the downstream 02 senser!

got a 2004 Nissan Sentra SER Spec-V w/113k and just now really hearing about the precat prob! good news my light came on for the p0420 code, and i looked it up and found these forums and thanks to the people on here i pulled my precat off and it was just about to start happening! on the other hand nissan didnt even try to find the screws for the butterfly valves that came out years back! I took off my cat and out popped two little B B's and from what i hurd those were the screws! I love my car, But after that will never trust the dealer again! anyways ive got this far by DIY!
Thank You to those people that posted all the info for it! you were a really big help!!!

 

[i68k]

Last edited by acespecv; Yesterday at 05:55 PM. Reason: P.s. Does anyone know how to extend the downstream 02 senser? going to put a aftermarket header on and move the downstream 02 senser behind the secondary cat! Any help whould be alot! Thanks again

the 04-06 already come with extended wires, your lower o2 is already on your midpipe. when you put a header on, you just need 2 antifoulers on the downstream o2, no need to extend it, it goes back in the same hole. otherwise, you must solder the wires for the o2, it is a voltage specific sensor.

 

[acespecv]

Thank you for the help, but if i just leave the downstrem 02 sensor were it is ill be reading the same exaust flow right? with the pre-cat on the primary 02 is befor the pre-cat and the other 02 sensor after. (the downstream is between the two cats)
so if i take the precat off and throw on aftermarket headers then both 02 sensors would be reading the same flow! "on the first page of the precat and butterfly valve screms" it showed the downstrem 02 after the 2nd cat?!?
Sorry if i miss understood you a.d.d to many things goin on at once my wifes car got a random misfire and drives like sh** and happened right after i took my precat and alt off
"Thanks again"

 

[i68k]

hope you replaced the alt after you took it off.

you need to use 2 antifoulers on the downstream o2 sensor, thats the sensor on your midpipe in between the cats. this will prevent you from getting an ses light when using an aftermarket catless header.

 

[acespecv]

? why would i need to replace the alt after taking it off?

 

[i68k]

....got a random misfire and drives like sh** and happened right after i took my precat and alt off....

you said you took it off with the header, just saying, hope you put it back on and the belt as well. if you start the motor without a belt or alt, it will misfire and run like ****, if it even starts.

 

[acespecv]

Oh okay, no haven't yet she's sittin in the garage! got a few thing to do to her while i've got her took apart!
P.s. needing to replace the head gasket, she's just now starting to get alittle oil on the outside of the gasket and been lookin around trying to get the best one i can get. Anyone know the best head gasket there is? dont wanna just throw anyone on and haft to do it again anytime soon cus i got a cheap one!
Thanks

 

[acespecv]

And if i smelled rotten egg smell out the car wouldn't that mean both the cats have gone?
I ask because it would be less work just to replace both at the same time then put on aftermarket headers and have the downstream cat welded on then haft to cut it back off later to have another put on to replace it!
Thanks again, and sorry for all the ?'s

 

[i68k]

look up information about the 07+ head gasket and 07+ head bolts, they are much stronger, if youre looking for aftermarket stuff maybe like ajusa headgasket and arp headbolts.