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Drove about 15 miles yesterday morning with no issues. Went out later in the day and it started sputtering about 3 miles after I left the house. Pulled off and checked the codes - only P0068 (Manifold absolute pressure / mass air flow - throttle position correlation). Cleared the code and started the car. It ran very rough, seemed like air/fuel/timing was messed up. Shut it off, same code. Tried again, same. Towed it home and fully cleaned/checked the front of the system from the filter to the throttle body. No obvious issues or potential vacuum leaks noted. Cleaned the MAF sensor, filter is fine. Checked plug wires as well, since I’ve been down that road before on my C6. Put it back together and got the same issue, then it wouldn’t start at all. Seemed like the starter locked up. Battery was on the charger. Given previous experiences, I’m thinking it could be as simple as replacing the battery, as I know that can cause issues and it’s due anyway. If that doesn’t work, it may be one of the sensors or ECM. Curious what others’ experience has been, if any, or if any resident expert has advice they are willing to share.
August 2, 2022 update. Unfortunately, Tinkertech wins the prize on this one. I had it towed to a dealer only to find that the engine seized up and no one can say why. Best guess is a dropped valve. So now I’m facing a full engine replacement with a quote around $20K. In researching this, there are a million things to consider, but I’m outta my league a bit as I don’t have the time or desire to micro manage the details of what should and should not be replaced. Any thoughts on this would be welcomed.
Last edited by TRH2002; Aug 3, 2022 at 08:22 PM.
Reason: Update about a month later
Do a load test on the battery to see if it's good.. they are a pain to get in and out.. Remember to disconnect that little right angle connector from the side of the battery that goes to vent tube.. they break off really easy if you try to remove battery with it on there. I hope it's something simple like the battery. Keep us posted..
Latest update, seems like it may be a bigger issue, likely computer/electronics. As suggested, and noted as my plan in my OP, I replaced the battery today. No issues with that, but it got weirder instead of better. After installing a brand new battery, the dash won’t even light up. The start button has an orange light and the dinging is working. Oddly, pinching the door handle (on either door) indexes the window downward each time, but that’s all it does. Had to pull the manual release to open the door. Hatch release button works fine. Same with remote, but the remote won’t lock or unlock the doors. It will turn the lights on (unlock) and off (lock, plus red security light on the dash comes on and flashes). Will leave it on the charger overnight, but not sure that will help. The battery date is very recent, so even a partial charge should start it, I’d think. Is it possible the battery is DOA? Any thoughts, or is it maybe time for expert assistance next week?
P0068 is a lot more involved than the things you checked. Here is the diagnostic procedure for the code. The procedures for the subsequent codes are included because the procedure for P0068 has diagnostic links that take you to sections of those procedures.
Your problems after the battery replacement are probably due to some glitch you introduced when switching batteries. Remember just because a battery is old doesn't mean it is causing issues. As long as it supplies the voltage required the car will work fine. From your original post, it looks like you only had one DTC. A low battery will cause multiple DTCs across multiple systems that aren't related to each other. I think when you get your post battery replacement problems cleared up you will find you still have DTC P0068. Just because a solution worked on a C6 doesn't mean it will work on a C7.
Next update, left it on the charger overnight. No change. A bit of reading and testing, the 350 amp fuse on the top of the battery appears to be blown. Not sure when or how it happened. I did not have a big spark or anything when changing the battery. So now what? Do I try just replacing that, or am I likely to blow it again due to a starter or other issue?
Another add: I read about 10 ohms connecting the negative to the “working” side of the positive leads (the top 2 in the picture) and about 4 ohms on the positive lead to the left of the 350 amp fuse.
Last edited by TRH2002; Jul 3, 2022 at 08:07 PM.
Reason: Grammar and add picture
P0068 diagnostic help, please!
