The application discloses a method and apparatus for providing a desired warning signal for a lighting unit. A coded warning system is provided employing a detection module (320) and a signal generating module (330), wherein the detection module is configured to obtain information regarding the detection of one or more operating parameters of the lighting unit and the signal generating module generates a desired warning signal (331) selected from a plurality of warning signals, upon determination that one or more of the operating parameters are abnormal operating parameters. Each warning signal of the plurality of warning signals is indicative of a specific abnormal operating parameter or a known combination of specific abnormal operating parameters.