Abstract
Keywords: emission, misfire, OBD II/EOBD.
OBD system is assembly diagnostic test, analytical and decision procedures realization in actual time for the purpose improvement emission efficiency and efficiency of components responsible for passive and active safety of vehicles. OBD system is integral components of vehicles with connecting with control module of engine (sensor, controller, actuator devices) One of the basic problem connected with OBD technology is test of on board diagnostic efficiency in different application. Self-diagnostic is to minimize the volume of substances generated by the combustion engines polluting the natural environment. Self-diagnostic is the basis for creating the best conditions for the most effective operation of the engine. Those paper include same results of testing and possibilities monitoring of catalytically converter in SI engine and simulating of signal from oxygen sensor. There are results of simulation of misfire in these engine.