These devices meet the strict standards of the National Highway Traffic Safety Administration (NHTSA), which regulates the overall safety of motor vehicles and the technology to make them operate safely and more efficiently. NHTSA’s standards do not permit IIDs to disable the engine if a retest is missed or failed. The IID can prevent the ignition from allowing the engine to start, but cannot disable the engine. If a random retest is failed or missed, state regulations may require that the vehicle provide physical indications, such as the horn sounding or lights flashing until a passing breath sample is provided or the vehicle is turned off.