Mine did the same thing. What had happened was I had a nail removed from one of my tires. Apparently, it still has a slow leak so every once and a while the "tire defect" message comes on. I had the dealer check all the electronics of the Tire Pressure Monitoring system and they were fine. This system uses the DSC sensors to measure the rotating volume of air in the tires (when you SET the system, it memorizes this setting). If there is any deviation in this rotating volume (like when it is cold out and the tire air volume actually decreases) or if one or more of your tires has lost some air presure the system will send you this message