Lexus RX 2010-15 :: Park Assist Warning Intermittently In Wet Weather?

Driving in heavy rain on the interstate, my park assist warning started signaling. I assumed it was the heavy rain affecting the sensors. However, later on local roads, I kept getting intermittent warnings, with only light rain coming down. It seemed to happen most during deceleration, when water would slide down the hood toward the front bumper. I'm guessing it has something to do with the sensors on the front bumper, possibly getting water in them.