Have you recently replaced any bulbs? Mismatched current draw will trigger the bulb out indicator light. When does the failed bulb indicator light? Does the bulb light when you turn on the parking lights, head lights, high beam, brake or turn signals. That is your clue to which bulb is defective. If it lights immediately after start up without tapping the brake or turning on any monitored lights the sensing black box may may be defective. FYI, the monitor does not notify you of defective interior light bulbs. Be sure to check the high mounted brake light too. Mark