Fault code P0420?
 

Plugged in the Durametric just for a check today, and it came on with P0420-exceeds limit value. I'm assuming it has something to do with bad 02 sensors as it threw a code for them not to far back. Any insight is very appreciated.

I believe that is for the right Cat. O2 sensors are P123X, where X changes depending on the sensor.

Well the code anyways is for the right Cat but it does not mean the right cat is shot. You can start by doing a bit of diagnosis. I would recommend switching the O2 sensors around to see if you still have the same code. IE, switch the sensors from right cat to left cat and if you still get the same error you know it's not the sensors.

Sent you a PM.

Regards,
paul...

P0420 is for Cat efficiency below threshold. The 2 sensors either side of the cat compared for Cat efficiency and flag if the cats are dead. hth

P0420 2002 Boxster
 

I just purchased (used from an independent dealership) 2 weeks ago.
(2002 Boxster I know she's "seasoned" but I like that model)

Last weekend Check engine light came on, went right back to the dealership and gave P0420 code. I was given a lame excuse by the dealership mechanic that it was sitting a while and being moved back and forth was possibly the reason.

How can I check this on my own or must a mechanic do it? Also why cant I find out the cost for replacement outside of a Porsche dealer? No one sells in California :-(

Time to have that talk, your baby has begun smoking the "mary jane", 420.....

No one wants to hear they need a new catalytic converter. Here is a link to some information you may find useful: P0420 Error Code: Catalyst System Efficiency Below Threshold (Bank 1) .

Hook your car up to a Durametric and plot the voltages of the pre and after cat O2 sensors. The pre-cat sensor should be almost a sine wave form, the after cat should be almost a straight line. If not, then its likely the cat is bad.