A control apparatus includes a first determining unit that determines whether a defect has occurred in an image based on print data printed on a sheet by a printing unit having print heads including a row of nozzles aligned in a direction crossing a sheet conveyance direction. A first instructing unit instructs printing of a test pattern to a print control unit configured to control the printing unit if the first determining unit determines that a defect has occurred in the image. A second determining unit determines whether a defect occurs in a test pattern printed on the sheet by the printing unit based on the instruction from the instruction unit. A second instructing unit instructs stoppage of printing to the print control unit if the second determining unit determines that a defect has occurred in the test pattern.