"Rear sensors" refers to devices or systems that detect or measure things happening at the back or rear of an object, vehicle, or machinery. They are used to provide feedback, warnings, or assist in navigation and safety. Full definition
The vehicle has a back up camera with rear sensors. (autolist.com)
The regular Moto Z will sport a 13 - megapixel rear sensor with laser autofocus, optical image stabilization and a dual tone LED flash for pitch dark conditions. (youmobile.org)
The camera department has a 16MP rear sensor along with an 8MP front sensor for cute selfies. (themrphone.com)