C8 Automatic Transmission Implausible Shifting

The symptoms do sound like they could be related to the automatic transmission fluid (ATF). Implausible shifting and emergency mode are common indicators. When the fluid degrades, it loses its lubricating and hydraulic properties. Are you familiar with how hydraulic fluid works in automatic transmissions? Also, has the ATF ever been changed in your C8?

I understand the basic principle of hydraulic fluid. But could undervoltage really cause the oil to degrade so quickly? What's the connection between the two?

Undervoltage itself doesn't directly degrade the oil, but it can cause erratic behavior in the transmission's electronic control system. This can lead to the transmission slipping or engaging improperly, which generates excessive heat. This heat accelerates the breakdown of the ATF. Given the symptoms and mileage, it would be best to have a workshop check the oil and the transmission's overall health.

Thanks for the detailed explanation. Replacing the transmission oil seems to have solved the issue. The total repair cost was 240€. Appreciate the help!