Codes are PO421 and PO431. Two errors for each code.
I am not super knowledgeable, please take everything with a grain of salt. I am very new to cars, but I have been looking into this issue for a while.
I have a 166k mile Spyder GS with the same codes.
PO421 and PO431 are the catalytic converter warmup codes. They seem to be a common problem on these cars. The codes are only referencing the two cat / header combo units in the engine bay, the large "main" cat under the car has no sensors and does not affect the computer in any way.
There is some information on this forum about these codes and potentially using o2 sensor spacers to fix the
false positive check engine light. It looks like some dealers were doing a ECU re-flash to fix the issue when the car was still under warranty.
This leads me to believe there is some kind of software bug with the ECU that causes the false positive reading.
Or, you know, one of the 4 o2 sensors
or one of the two cats are worn out and need to be replaced. You should also make sure all of the o2 sensors are plugged in haha.
Let me know if you fix it, I have still not tried the sensor replacement / spacers. I have just been driving it with the engine light and pulling the codes every once and a while to make sure nothing new has come up.
EDIT: Thank you Sabertooth for telling me I was wrong! Please read his reply. Dealers were also replacing the cats with the re-flash. Spacers only hide the engine light. Looks like fix is probably either sensors or a cats. There is info on which one you need / where in
this thread, including a PDF with what all the codes mean.