could be one of the backup sensors is not working or possibly needs calibration or maybe a bad connection, I would check the connector on each of the 4 backup sensors make sure they are clean and snug. there is a troubleshooting method to check the backup sensors but one way you can check each one is get a helper and go into a space where there is nothing behind you, put the vehicle in reverse with your foot on the brake then have someone go the rear of the vehicle and while standing to the side of the rear bumper have them place there hand over each sensor one at a time, each sensor should beep, if one does not beep then you know that is the one that is bad or doesn't have a connection.
2016 Yukon SLT. It came up once before a few months ago. It just came up again. Only comes on when in reverse. Once I cycle the ignition it goes away. Have any of you experienced this before? If so, what’s the remedy.
