An electro-optical imaging reader includes a chassis mounted in a housing, a window spaced from a rear wall of the chassis, an imaging module for capturing return light from a target through the window over an imaging field of view, a controller for operating the reader in a standby state in which no target is read, and for processing the captured return light to read the target during a reading state, and an object sensing assembly supported by the rear chassis wall and spaced from the window. The object sensing assembly senses the presence of an object bearing the target in front of the window by detecting return sensing light from the object through the window over a sensing field of view that at least partially overlaps the imaging field of view, and triggers the controller to change from the standby state to the reading state upon such detection.