Corsa Automatic Gearbox Problems

Worn transmission oil is a definite possibility with those symptoms in an older Corsa. The oil loses its lubricating properties over time, leading to poor shifting and potential damage. Have you checked the oil level and condition? If it's dark, sludgy, or smells burnt, it's almost certainly time for a transmission flush and oil replacement. Given the undervoltage suspicion, has the car battery been tested recently?

I haven't checked the oil level yet. Where exactly is the dipstick located on this model? Also, could low voltage actually cause these shifting problems, or is that a red herring?

On your Corsa, the dipstick for the automatic transmission should be near the front of the transmission itself, usually marked with a yellow or orange handle. As for low voltage, yes, it absolutely can cause shifting issues! The solenoids that control the gears rely on stable voltage to operate correctly. Erratic voltage can lead to erratic shifting, or even put the transmission into limp mode. I'd recommend a diagnostic check at a workshop; they'll be able to pinpoint the problem.

Thanks for the advice! Took it to a shop, and you were spot on. Turns out the automatic transmission oil was worn, causing the issues. An oil change set me back 240€, but it's shifting smoothly again.