2011 Lexus IS 350 User Guide - Page 87

1-6. Theft deterrent system Engine immobilizer system The vehicle's keys have built-in transponder chips that prevent the engine from starting if the key has not been previously registered in the vehicle's on-board computer. Never leave the keys inside the vehicle when you leave the vehicle. The indicator light flashes after the "ENGINE START STOP" switch has been turned OFF to indicate that the system is operating. The indicator light stops flashing after the "ENGINE START STOP" switch has been turned to ACCESSORY or IGNITION ON mode to indicate that the system has been canceled. n System maintenance The vehicle has a maintenance-free type engine immobilizer system. n Conditions that may cause the system to malfunction l If the grip portion of the key is in contact with a metallic object l If the key is in close proximity to or touching a key to the security system (key with a built-in transponder chip) of another vehicle 94