The codes pulled are saying different things including O2 sensor and bad cat converter. I've tried fixing several times, dropped over a grand doing so, but the light always comes back. Quite frankly I'm done trying to fix it at this point (same old sob story). Some mechanics won't even look at my car because I have aftermarket exhaust.

Anyone had the same problem, anyway around it?

O2 simulator.

Post the codes your getting.

wow that simulator sounds ingenious but risky...

im getting P0138

P0138 is a downstream O2, after the cat. So your aftermarket exhaust is most likely the cause. A simulator will solve your problem. They are easy to install and it will keep your check engine light off so you can pass inspection.

sorry to jack someone elses thread but i had a similar problem. its time for my state inspection and im throwing code P1335 and need a quick fix fast but dont know what to do!

o2 sims get rid of the CEL but from my expereince they DO NOT let the emissons systems goto ready on 4th gens. In Massachusetts you cannot have any CELs and all emissons systems must be ready. I had to do some brain work and alot of harness rewiring to get my car to pass emissons.

There's alot of work done to my car, many parts are not stock including the catback. Thankfully the shop I goto doesn't know a stock Maxima let alone a modified one so I pass the visual testing. They are also Harley biker guys so they don't care about loud exhausts on anything. (all aftermarket exhausts are illegal in Massachusetts, but rarely enforced)

Anyways IMO if the cat converter and suspect o2 sensors have been replaced it's time to take out the multimeter and check out the wiring.