Hi guys,

Series 1 07 RX8 owner here.

Getting error code p0420 appearing a few days after resetting the ECU.

Im assuming that my cat has already been gutted or decatted, but im not sure how to check? Are there any signs i should be looking for to to find out?

I've read that P0420 is caused by either a bad cat or a bad rear o2 sensor so im a little worried.

Thanks

 

The exhaust smell is a giveaway if you have a cat or not.
With a cat, you car will smell like any other on the road, meaning a light smell with nothing particular to it.
If you don't have a cat, the smell will be very strong, almost eye watering if you stick your face in there. Motorcycles, go karts and lawn mowers have similar smells because they also don't have cats.

I would also say catless increase noise levels, but that can vary depending if you have the stock muffler or a high flow catback.

 

That code usually means its a decat but if you don't know for sure, you are best to take off the cat and inspect.

 

If you have stock catback with that code you better hope you have a decat else your cat is on its way out and that is not good for your engine.