GAMESHARQ

I own a 2014 Lexus RX 350.

Earlier today, I had the engine turned on as I was standing outside of the vehicle washing it.

While I was doing that, I heard a long beep (about 5-10 seconds) so I got inside and noticed two warning lights on the dash.

One was a flashing yellow exclamation point.

The other one said "TURN ENGINE OFF".

So I turned the engine off and when I started it back up again, the warning lights were gone.

Does anyone know what would cause this?

Clutchless

Was the key in your pocket? It may have been warning that the vehicle was left running with no key inside. I would check your oil and coolant levels.
Next time turn the car off to wash it. Why would you leave the motor running?

GAMESHARQ

That may have been it.

I left the motor running to keep the AC going since it doesn't take me very long to wash it.