Bad cat help '03 S
 

Hi Crew,

I got a check engine light on my '03 S. An evaluation with my Durametric tool showed P0430 Porsche fault code 45 - Cat conv efficiency bank 2. When I looked at bank 2 pre and post O2 sensor voltage, they are both making similar wave length oscillations. Based on what I have seen, this means that the cat is toast. I am in an area where smog testing is not done. So I could replace the cats with test pipes, but how would I keep the check engine line from coming on?

Any feedback would be appreciated.

Thanks!!!

OBD can be a funny thing.

Sometimes, for example, a bad MAF Sensor can cause codes associated with "downstream" components.

It's seldom 100% that the code accurately describes the problem with respect to emissions components.

Before I would decide that the cat has failed, I would do something easy that doesn't cost $ by swapping the post O2 sensors between banks and see if the problem follows to bank 1 (P0420), then you would know know that the post O2 sensor needs to be replaced.

BTW, the factory diagnostics mention the possible fault causes, in this order, to be:
1) The pre- and post- O2 sensors were exchanged
2) valve lift fault
3) aged post O2 sensor
4) cat failure

Regards,
paul...

If you are going to remove the CATs and don't want a CEL, you have a couple options:

1. Flash the ECU ($800-$1200). Has the added benefit of some added power.
2. Install a couple of "Mini Cat" spacers: Link

I did #2 when installing my sport-cats because the measurement was very strict on my stock Cayman S. ECU Flash comes later with some other goodies.