A printing apparatus includes a carriage, a first detector module, and a second detector module. The carriage may selectively move a fluid applicator along a scanning path in a first scanning direction and a second scanning direction across a print zone to print on a media therein. The first detector module and second detector module may be coupled to the carriage. Further, the first detector module may include a first receiver and a first source to form a first detection region there between downstream of the carriage in the first scanning direction to detect an object therein. The second detector module may include a second receiver and a second source to form a second detection region there between downstream of the carriage in the second scanning direction to detect an object therein.