I installed my (budget) y pipe and reset the ecu and the next day i recieved the CEL,(Codes 0510,0512) I installed the fact 02 sensors (46,500 miles)and a test pipe off ebay and got these codes, oh yeah also got the bees in the can ;0) But the first day of driving back and forth to work approx 30 miles everything was fine, except my axle back aftermarket muffler got allot louder. Kind of to loud for my taste so i put my fact one back on and that day is when i got the check engine light? maybe backpresure? Any one had this experience? Is it that dam test pipe? or did oxygen sensor crap out?
Thanx

 

im thinking its a o2 sensor, not backpressure.

 

i have the same thing...
i installed my budget y last saturday morning & cel came on in the evening...
i haven't pulled it for codes yet but I think that resetting it again might do the trick...

Sam

 

anyone else??????????

 

An air leak upstream of the rear O2 sensor can trip a CEL (0707 for earlier 4th gens). Check your bolted connections for leaks and reset the ecu. Did you use new gaskets?

 

oh, man...so now i have to go under the car again???

darn....

 

Did you check the codes with an OBDII reader?

 

Well, I reread your post a little more carefully.

A test pipe will trip your CEL with a code for the rear heated O2 sensor, even if you have no air leaks. The rear O2 sensor looks for a variation in O2 as compared to what the front O2 sensors are sensing. A difference in O2 detected by the rear sensor indicates that the cat is doing it's job. No difference is an indication that something is wrong, hence the CEL. Since you have no cat, you get the CEL.

There was a recent thread about this very thing and how you can use an ebay item to trick the ecu into thinking you have a functioning cat. I'll have to look for it.

Found it: http://forums.maxima.org/showthread....ighlight=baker