So, over the past couple of weeks I began to suspect my cat was failing. I noticed a small drop in power in the mid to upper RPM ranges, my fuel consumption had gotten noticeably worse, and occasionally I'd have a few small exhaust shudders under low throttle. I had been keeping an eye on it, looking under the car to check if it was cherried after driving, but a visual inspection revealed nothing out of the ordinary. Yesterday I finally got a CEL on my way to work and made an appointment with the dealer. Sure enough, the cat was operating below threshold - no surprise there. Surprisingly, the dealer had a cat in stock and my car was ready for pick-up in about two hours. Now, here's my question...

I just got the car back and took a quick look underneath after the drive home, which is only about a 15 mile commute from the dealer. Crouching down and looking from the driver's side, there's a small circle where the air sensor plugs into the cat that was glowing red. It also seemed exceptionally hot, much hotter than the one I just had replaced. Naturally it smells terrible, but I'm assuming that's from the anti-corrosive aluminum/zinc powder that most new exhaust components are coated in. I've only owned the car for about 5 months and it has nearly 50,000 miles on it, so I don't really have a good point of reference for "normal" cat behavior since I apparently bought it with a half-dead cat. So I guess my question would be...is the small glowing circle normal or was my old cat so far gone that it wasn't even operating at the correct temperature? Should I be alarmed, or am I worried about nothing?

A little history on the car: Stock 2004 GT 6MT, only one previous owner with pristine service records, all recalls performed, original engine still pulling strong with plugs and coils replaced at 45,000 miles.

 

I was wondering the same thing. I got my RX8 out of storage yesterday, I used it all day and it pulls much better than ever (new coils, old were long gone and dealer only said 1 was bad... changed all 4).

I got home yesterday at night and decided to take a look at my cat (by leaning on the ground) and I saw exactly what you describe, glowing red hot right around the O2 sensor. I have less than 25k miles on it but I ran with bad coils during the end of last summer. I am really wondering if my cat is blocked (possibly melted from running on bad coils?). The car runs wonderful and pulls a lot more than last summer so I guess exhaust isn't blocked (or partly).

I guess the catalytic converter is part of a longer warranty, since it's a pollution control device?!

I hope people here can confirm our problem or standard behavior!

 

bump... also OP, you could change the title to "red hot cat" to catch the eye