RandomMoon

Keith... there's also a thread on this in the DIY for 993 in this Forum... it looks like at a couple of guys have figured out how to reset them! (but also confirm a prior $300 trip to the dealership).

Keith, I live in CA (where SMOG emissions are tight) and have a 97 993 Carrera S. Bot it with 16k in '00, has 48k now. I have been driving the car much more often these days, however, early on, I did keep it in the garage looking pretty and not driving much. Great to keep the low miles, not so great for the battery and car overall. Porsches like to be driven. Anyway, when I read your post about the smog testing/failing, I was compelled to chime in. I have had the same problem with passing smog with the low/disconnected battery scenario... basically, if the battery amperage gets too low, or is disconnected, some of the OBD codes that the CA (and probably TX) emissions tests look at are faulted. Having these in the faulted state causes the smog guy to give you the thumbs down... Insult to injury: It takes a specific set of steps (certain speeds in certain gears for a certain duration of minutes/seconds in a certain sequence) and, from what I can ascertain, the dealership (or decent pro-shop) computer voodoo to get these codes to reset to where they PASS the SMOG test... these codes do not just reset themselves after 20 minutes of driving. (like some other cars). I have had to do this twice now since I've owned the car. Each time it ran between $150 and $200. I've seen this mentioned on other 993 specific boards here and there... but, I think it mostly applies to the tighter emissions states... I believe there are other states which ignore this particular set of OBD codes completely. Other 993 owners feel free to chime in here. My lesson learned: If you are going to stable the car, or live in cold weather climate, get yourself a good (Porsche approved) battery charger and hook her up. Also, if you have a shop do major work (like dropping engine to install a new clutch), have them ensure you that they will reset the codes such that you'll still pass smog given they will likely have disconnected the battery as part of the work. Otherwise, come smog check time, you'll be heading over to the dealership to pay them $200 just to reset the codes, and then back over the SMOG guy for the retest. BTW, the $200 is for labor time only, no parts are required. No other work/tuning is done, they just get the codes to reset... what this means is that if the car passes SMOG after the codes are reset, then it would have passed before getting the codes reset... and the $200 is just a penalty that 993 owners take thanks to some much needed, but ill-directed, smog legislation. All that said, I love this car and wouldn't trade it for my left lugnut. ;-)