Rattle from rear catalytic - pinched exhaust pipe?

[Sayantsi]

So, yesterday I noticed a new rattle on acceleration. Nothing when idling but once I get rpm over 2k or so, I get a rattle noise. That night, the CEL popped up - no time to read the code yet though.

This morning, I go out and start inspecting the exhaust system and sure enough, the catalytic on the passenger side just ahead of the muffler is rattling when thumped.

I continued to inspect the heat shields and exhaust and also discovered that the exhaust pipe is slightly pinched where it goes between the rear suspension and the body - I'm guessing a road bump brought the two close enough together that the pipe got flattened a bit.

So... a couple questions.

One - does the rear cat get read at all by the car with any A/F or O2 sensors? Can I just gut it or run a straight pipe?

Two - how likely is it that the pinched exhaust is causing excessive backpressure and damaging my cats?

Thanks in advance.

[RacerZX]

Odds are good your pre-cat is crumbling and the debris is plugging up your main cat, this is not at all uncommon on the R51 (happened to me too with my V6). Both will need replacing and should be covered under warranty.

[Sayantsi]

Thanks. I stopped by and got the cel read - P0420 sensor reading below threshold.

I was wondering why the cel popped up and I have loose material in the down-level cat - it sounds like the monitored cat has gone and its material is now rattling in the second cat on the passenger side, which is "bank 1" I believe.

And the Pathy has 85k mi, so no more warranty...

[RacerZX]

At least here in California, emissions related equipment have a longer warranty...but I'm not sure if that's just CA or Nissan wide.

[Sayantsi]

Thanks - afaik, Federal policy is 8 yrs 80k mi... I can still call the dealer and see if they will goodwill anything...

[eieio]

Thanks - afaik, Federal policy is 8 yrs 80k mi... I can still call the dealer and see if they will goodwill anything...

Nissan & goodwill in the same sentence?
lotsa luck

[NVRDONE]

I had my cats fail at 88k and nissan would not help / goodwill etc saying the warranty was only until 80k. And I worked for a nissan dealer at the time !
Anyway, now at 120k mine are starting to rattle again. The replacement warranty was 12 mo / 12k. So now I'm just going to gut all 4 cats and use spark plug extenders on the o2 sensors so the cel doesn't go of. Where I live we don't have emissions inspections.