The emission of greenhouse gases by human activity has become a nuisance to the balance and safety of the environment. One of the greenhouse gases that is emitted by human activity is nitrogen oxide or nitric oxide (NO). This project was completed by using all the Arduino-compatible components and parts. The aim of this project is to develop an NO detector that can be used for detecting the emission of NO from motorized vehicles and testing the reliability and accuracy of the gas detector to detect the gas. The reliability and accuracy of the gas detector are measured by comparing the readings from the constructed gas detector with the readings from a trusted gas detector available at PUSPAKOM Seri Manjung. There are four parameters that will be measured using both gas detectors in this project, which are engine revolutions per minute, engine capacity, types of fuel used, and exhaust temperature. The testing involved 25 vehicles with different criteria according to the parameters mentioned above. The result shows that there is a strong relationship between the emission of NO and the temperature of vehicle components, especially the engine. One of the factors contributing to such a result is due to the reactivity of the NO with its surrounding temperature.