I have a 2021 Prime and occasionally, when EV mode is selected with a full charge it stays in engine mode until I turn it off and back on. Then it runs off the battery. The weather is never very cold or hot? Anyone else experiencing this?
There are things that will cause the gas engine to run. Merely running the defroster can do it. Once the internal combustion engine (ICE) starts it will run until it’s warmed up. There are lots of discussions on this topic.
when you start the car, it should be in ev mode, unless you chabge it to hv or auto. or id any of the things schja01 mentions bove
It's never a good idea to manually shut down the ICE in a Prius while it is still running. The computer has decided the engine needs to be running, and you're better off letting the computer turn it off before powering down the car. Usually, the ICE needs to complete its warmup before it should be shut down. Just select Park, turn OFF the HVAC (engine could be running to provide cabin heat) and let the computer shut off the ICE--then Power down the car down. Not letting an ICE achieve full operating temp will leave unburned hydrocarbons (fuel) in the oil and excess water vapor in the exhaust system. Both are bad for the longevity of the car.
