cat not ready

'Listers, anyone that can shed some light or point me in the right direction; Car is an '02 c4s with ~76k mi. which is due for it's Calif. bi annual smog check. Smog guy says ready code for the cat fails. Now i don't have/had any CEL's. Car is my DD, but it did sit up for ~a week recently. No battery issues. I don't have a code reader but i do have the Enthusiast version Durametric. When i got home from the smog shop i hooked up the Durametric and sure enough, under 'ready status' everthing else shows pass with the execption of the cat's. After searching this forum, i decided to let engine cool overnight. This am i hooked up the durametric and everything was showing pass so off to the smog shop. Upon disconnecting the Durametric and installing their reader once again 'not ready'. Called Durametric, apparently the tool does not refresh automatically. So i'm wondering what is this telling me. Initially pass but then fail. the shop says Cats are not bad just drive it, but i do. I've done the drive procedure on a 993 and my search yield here mentions i might have to perform the same procedure on the 996. Anyone BTDT? Tia.

Maybe you should try some of the procedures here - https://rennlist.com/forums/996-foru...t-ready-2.html

I was playing the waiting game with my '02 996 -- LOTS of driving and still wondering why cat test in particular wouldn't clear -- followed the procedures referenced above and here . The second piece in particular (drive 20-30 mph for 3+ minutes) did the trick. I did not need to follow the entire sequence. As others have noted, these driving patterns may not be part of your usual MO so try before you get frustrated! 26-28mph for 3+ min seemed like an eternity but, Cat test passed almost immediately (I use Torque with a bluetooth OBDII reader from Amazon) so back in business. Thanks to everyone for the posts on this topic.

Lots of varying interpretations of the reset procedure. The following worked for me, courtesy of a respected RLer. I would get a real time reader that transmits to your phone, it takes a lot of the guess work out. Note the last bullet says you may need to do this more than once to get the Cat to clear. Another note, I cleared the DME as soon as I got the scanner, that might have been key. Good luck. - Start car and idle for 2 min (SAI pump should be ON and then OFF) - Start driving the car but try to keep the rev below 3k at all times. Just drive 10-15 min local roads, then 10-20 min freeway. The trick is NOT to go over 3k if possible because most tests require rpm < $3k (or engine idle) to perform. Also, on freeway try to maintain as constant speed as possible (rpm < 3k). - Park the car but leave the engine idling for 5 min or so - Now all your readiness flags should set (maybe except the cats). The cat readiness may need the same driving on the NEXT day to set if the cats are healthy.

Just an fyi... My car finally passed. I don't know which part of the drive cycle did the trick and frankly i don't give a damn but i firmly believe 'throttle angle' is very important as i had done the drive cycle a few times near where i live but in retrospect the flatter the road the better. Thanks everybody who posted.