Defeat devices

Defeat devices are software or hardware tools installed in vehicles to temporarily alter emissions control systems during testing. They detect when a car is undergoing official emissions testing and adjust engine performance to produce lower emissions, helping the vehicle pass inspection. However, during real-world driving, these devices deactivate or reduce their effectiveness, resulting in higher emissions than allowed. This practice allows vehicles to meet legal standards in laboratories while actually emitting more pollutants on the road. Defeat devices are considered deceptive and are illegal in many countries, as they undermine efforts to reduce air pollution and protect the environment.