Oakmax

I think you are suggesting that the 12V battery is at end-of-life and is no longer capable of being sufficiently charged via the dc/dc converter. Is that accurate? I will continue to monitor the car until I can get a good reading while the wrench light or check engine light is on.

Ok. Thank you for giving me a thread to pull on. I purchased an OBD scanner and I received the following error codes upon starting the car. Secondary OBD Control Module C U0198:00-2F. Lost Communication with Telematic Control Module A Accessory Protocol Interface Module U0198:00-0B. Lost Communication with Telematic Control Module A U3000:04-0A Control Module -System Internal Failures DC to DC Converter Control Module U0412:00-28. Invalid Data Received from Battery Energy Control Module A It seems like there is some bad communication between the DC to DC converter and maybe the charging system? This seems consistent with losing power to the 12V electrical system while driving. Maybe the DC/DC converter isn't charging the 12V battery appropriately. Might this be a loose connector somewhere?

Thank you. That sounds like a good first step.

Hello all, I purchased a used 2016 Cmax Energi a couple of years ago. It had been operating normally until it was rear ended while parked. The damage wasn't super severe, but I did have to have the rear liftgate and bumper replaced. Also, the front grill of the vehicle was damaged when it was pushed into the car in front of it. A few weeks after I got the car back, on one of the first hot days of the summer, I had the a/c blowing and I got the "Yellow Wrench" indicator light on the dashboard. The vehicle drove fine and there were no other issues. After stopping the vehicle and letting it sit overnight, the yellow wrench went away. I continued to commute to work in the vehicle (about 40 minutes) without any incident. Then on a warm day I used the a/c again, and after a while, the yellow wrench came back. But then it went away again after letting the car sit. Then I went on a particularly long drive on a hot day. I held off on using the a/c for about 30 minutes, but then I had to put it on. After a while with the a/c on, the yellow wrench came on, then the check engine light came on. Of course I turned the a/c off. Then eventually the Battery Light came on. Then the center console said something about shutting down. So I turned everything that was an accessory off and the console came back fine and the battery light went off. I was out in the middle of nowhere so I was a bit nervous. I was able to limp to my destination and shut the car off for a while. When I restarted it, everything appeared fine. No warning lights. Until I drive again for about 40 minutes using something that drains the battery. Then I get the wrench. Even headlights will do it. 12 Volt voltage reading at jumper posts is 12.3 resting. voltage reading with car on is 14.5 12 volt reading via et mode after morning commute is 12.9v There are no DTC codes in ET mode. Took it to autozone and they could't read any codes either. I don't know if this was a pre-existing condition that the car had prior to the accident or if something might have happened during the accident/repair. Any thoughts? Thanks for your help.