I need some help here, Today my "check engine light" beamed on. I took my car to the Nissan dealer and the computer came up with an error code P0402 (pre-cat is missing). I have a Warpspeed aftermarket Y-pipe and of course it doesn't have a Pre-cat installed for last 3 1/2 years with no problems till now. what are my options. I do not want to convert my car back to the stock Y-pipe (Nissan suggestion). the technican thinks my main catalytic converter might be bad and can no longer handle the load without a pre-cat installed. also my car needs an inspections in a few weeks..................I need an solution to this problem.

 

I've always heard that if your cat is bad, your exhaust will smell like rotten eggs. I'm willing to bet your cat has gone out.

 

Well, my exhaust doesn't smell bad at all, I looked thru the posts and error code P0402 is listed as "fuel tank Temp sensor"...........which is correct

 

That's what the Haynes manual lists for 0402 as well.

 

Hope its easy to change out. Good luck!!

 

I'M Sorry guys...............the Error code is P0420 not 0402............I mis-read the paper.........

 

Scan tool trouble code P0420 is catalyst system fault (right bank). There is no CEL flash code for 0420.

 

(Right Bank ?) is that the right 02 sensor or the Cat itself. I don't have a pre-cat. if the car has been passing inspection for 3 years without a pre-cat why do I need it...

 

I don't know much about CELs. I am just going buy the Haynes manual. The mistake 0402 code you gave eariler was the CEL code, not the scan tool trouble code listed next to it in Haynes. As I said there is no CEl 0420 code, just a scan tool trouble code.

Perhaps they have misread the code.