Livinia transmission indicator light issue

Could be. Is the cooling fan running constantly, even when the engine isn't that hot? A faulty pressure sensor could cause those symptoms and throw those codes. Have you checked the connections to the sensor? It’s part of the cooling system, so start there.

The fan seems to cycle normally, though I haven't paid super close attention. Where exactly is the pressure sensor located? I'm not sure where to find the right plug connection in the engine bay.

It varies by specific engine configuration, but it's usually near the radiator itself or on one of the coolant lines. Given the transmission symptoms and error codes all pointing to pressure, but without being able to physically inspect the sensor, it may be worth having a workshop take a quick look to rule out further cooling system problems.

Thanks for the input! I took it to a local mechanic, and you were right – turned out to be a faulty connection to the pressure sensor, just as the error memory suggested. They cleaned it and secured everything for 95€. Shifts like new now.