back up sensor keeps buzzing

[Gui272]

I just picked my truck up yesterday. On my way home i went to the car wash and cleaned the truck up. It's around 20 degrees outside here. Before i sprayed the truck off the reverse sensors worked find and now they just keep buzzing.

I did look and see if maybe it was frozen over top of the sensor but that didn't seam to be the case.

Does anyone have any suggestions or experienced this?

Thanks,