Beg, borrow or buy an OBD scan tool that has the readiness check feature. I purchased mine at HF for +/- $50. There is also a specific driving protocol for setting the system. I believe this will also work for a 986 as well. My wife's Volvo also has a very similar ritual required to set all of the systems. It can take a couple of cycles to get them all set. Good luck.
OBDII readiness drive cycle procedures - Pelican Parts Technical BBS
1997 Porsche Boxster
2018 Porsche Macan
Threaded Mode
