p0304 Code - 997.2
 

I took my 911 in for emissions, and got the "monitors not ready" error... assumed it might have been if the shop has disconnected the battery during a recent springs install and wheel bearing replacement.
After driving it around for a couple of days to get the monitors ready, I got a check engine light. After restarting the car, I checked it with the OBD reader and saw the P0304 code.
Any thoughts on what this means? It may be my imagination, but I think the car was also running a bit rough around the time this happened.

thanks!
https://cimg8.ibsrv.net/gimg/rennlis...451ac07ea6.png

If it's any help, looks like the monitor that was not ready earlier was the EGR/VVT one... (the catalyst had become "ready" soon after I took this screen shot)


https://cimg9.ibsrv.net/gimg/rennlis...173fe28530.jpg

How many miles on the car and how long since plugs and coil packs have been replaced? If more than 30,000 miles that's probably what you need and you might as well do all of them as it will just be a matter of time before the others go bad and do the same thing once one fails. The other thing that can cause a misfire in only one cylinder is low compression, but that's unlikely and it's probably just the plug or coil pack.

Thanks- car is a 2010 and has about 75k miles, plugs are about a year old. I don't think the coil packs have ever been changed.

If the battery was disconnected for a while, then the computer has to reset itself.... someone here knows the official words for this process.... something about readiness or whatever..... It takes some elongated driving time before the car knows itself.

Check out #28 here... this is for the 996 but I am sure the issue is the same for all of our cars.... process may be different... do some more research: https://rennlist.com/forums/996-foru...t-ready-2.html

Peace
Bruce in Philly

Update on this- looks like it was indeed a cracked coil. I went ahead and had all of them changed as they were reported to be due, drove around for awhile and saw no pending codes. And passed my past-due emissions :)

Good deal. I assume you did new plugs at the same times so you should be good for a while.

The new style coil packs with the thicker insulator back section (require longer screws when upgrading from the old 997.1 style) are supposed to last longer before cracking and the reason for the update. I'd leave them alone until you get misfires. They'll show up first when driving in the rain.

I decided to not change the packs on my 2009 C2S until I get a misfire.... or something points me directly to them as an issue. I have 130K miles on it now and have done all my plug changes myself at 40K intervals.... I could have done it at relatively low cost but decided not to. FWIW.

Peace
Bruce in Philly