Hello, everyone

My 997T has aftermarket exhaust with 200cell cats and software.
In the last two months since I bought the car I had CEL coming up twice while I was driving slowly warming up the car. After a couple of days (10 or so ignitions on and off) the CEL disappears.
Has anyone of you ever had this kind of strange behaviour?

 

I was having that kind of CEL issue when I switched exhaust also. I just got a tune and now everything is fine.

 

I am quite sure this is due to 200cell cats. I had a similar problem in my previous tuned car (Audi). What I am curiouos about is why CEL disappears after some time, does the computer learn and delete the error?

 

Under many conditions the cats perform within spec - hence the intermittent nature of the CEL. It is quite possible that just a spacer on your O2 sensor would also fix your problem. It's just a good reason to get a tune.

 

very common, flash it to turn the post cat sensors off or better, get a Europipe exhaust which wont do it period due to their exhaust cat housing design, not just the cat materials. Most exhausts will cause a CEL sooner or later (in regards to a post cat sensor, too rich etc).

 

http://www.bigdaddiesgarage.com/mini-cat-cel-fix.html