Flex Transmission Implausible Shifting

Dude, that sounds REALLY familiar! I had similar craziness with my Flex – though I can't remember the exact mileage when it started. My transmission was acting all kinds of possessed! Tell me, have you checked your battery lately? Low voltage can mess with the computer that controls the transmission. Seriously, that's what was causing my transmission to throw a fit! Is your car battery working fine?

Interesting thought! I haven't specifically checked the battery voltage, but the car starts fine every time. Could a slightly weak battery still cause these transmission problems, even if it's enough to start the engine?

YES! Absolutely! That's EXACTLY what happened to me. It doesn't take a completely dead battery, just one that's not putting out enough juice consistently. The computer gets wonky signals and freaks out, causing the transmission to act stupid. I'd get it checked ASAP. Honestly, I’d advise you to take it to a reputable workshop.

Thanks for the insight! It turns out you were spot on. The battery was indeed the culprit, causing undervoltage. Replaced it, and the transmission is shifting smoothly again. Total cost was 240€.