99 Altima ???

I have a 99 Altima and i recently did some upgrades. Now I did a all new exhaust system with headers. Altimas in general comes with 2 catalytic converter 1 in the exhaust maniflod and 2 on the pipe.. Now the problem is my check engine is coming on and then after a month or so it goes away but then it comes back after a day or two. my new headers is the 4-1 setup which means only 1 catalytic converter is persent. I checked and the ecu is looking for the second converter. What should I do??? any suggestion.


P.S. also is a Maxima swap possible in a Altima.

well, you should get a 4-2-1 headers since the ecu is looking for 2 cats.
and no, the vq30 maxima engine does not bolt right on. youre better off turboing the ka24de