DT*: THE CONTACT STATED THE VEHICLE WAS PARKED FOR OVER AN HOUR, WHEN THE HEAT SHIELD ON THE TOP OF THE EXHAUST SYSTEM BEGAN TO SMOLDER. NO INDICATOR LAMP ILLUMINATED PRIOR TO THE PROBLEM. THE FIRE DEPARTMENT WAS NOTIFIED AND CAME, ALTHOUGH NO FLAMES ERUPTED. THE FIRE DEPARTMENT COULD NOT DETERMINE THE CAUSE OF THE SMOKE. HOWEVER, AN INDEPENDENT MECHANIC INSPECTED THE VEHICLE AND DISCOVERED THE CAUSE OF THE SMOKE WAS THE HEAT SHIELD.