The current practice of gasoline engine emission examination is partially based on λ reading. For the λ value of a car over a specific standard, it indicates the car failed the examination. Although modern automobiles have built-in λ sensors to monitor the efficiency of the catalytic converter and can warn the driver when the converter breaks down, mandatory vehicle examination cannot be taken every day for each car. The concept of telemetry with traffic lights is proposed that allows λ data collected from the vehicle on road to be reported immediately at a traffic light. The data can be sent via a radio transmitter in the vehicle to a radio receiver mounted on the traffic light which is connected to a server. So, the authority can monitor the engine emissions via computer networks while the vehicles stop at red traffic lights. Experimental results show that the idea is feasible