Q: powertrain warning light came on the car went into limp mode

Hello. The power train warning light comes on when the computer detects that there is an issue with the vehicle that could potentially damage the vehicle. This is why the vehicle is put into reduced power mode, to reduce stress on the engine and components, reducing the likelihood of damage. If the light went away and the vehicle’s performance was restored after restarting the engine then it may be possible that there was only a momentary malfunction. The fact that full power was restored is a good sign, however that does not mean the issue could not return. Intermittent issues like these can sometimes be difficult to diagnose if the light has gone, however you may be able to scan the computer for any potentially stored codes, which may shed some light on what the issue could be. If you are unsure I would recommend having a professional technician, such as one from YourMechanic, come to your location to determine if your vehicle is in need of repair.