Prius Electrical Issues

Sounds like a pain. Undervoltage could be the culprit, especially with those symptoms. A weak battery or a charging system problem could definitely cause that. Have you checked the battery voltage? A healthy 12V battery should read around 12.6 volts when the car is off. If it's significantly lower, that's a red flag.

Thanks for the quick response! I haven't checked the battery voltage with a multimeter yet, but I will do that first thing tomorrow. If the battery voltage is indeed low, what would be the next step? Could it be the voltage regulator or perhaps the alternator? Or maybe it is simply that the battery is heavily discharged?

If the battery voltage is low, it's likely either a heavily discharged or defective battery. A voltage regulator issue could cause undercharging, but it's less common than a bad battery, especially given the age of your Prius. An alternator issue is less likely since it's a hybrid, but still possible. Honestly, it's worth getting it checked at a workshop to be certain.

Thanks a lot for your help! I checked the voltage as you advised, and it was indeed very low. I took it to the workshop, and they confirmed that the battery was heavily discharged and defective. They replaced the battery, and now everything is working perfectly again. The repair cost was 290€.