Pollutant emissions from vehicles are responsible for about 60% of air pollution in urban areas. Also, the greenhouse gases production (especially CO₂ from transportation sector) represents the actual global issue. In order to reduce the amount of CO₂ level, active measures needed to be adopted. For this study it was established and tested an engine cleaning method, for carbon oxides amount from exhaust gases diminish. An authentic engine cleaning test cycle is used: different engine speed regimes at different time intervals are used for the tested vehicle. The cycle duration was set at 40 minutes. Before and after the cleaning cycle, emissions data are collected from vehicle exhaust pipe. The emissions of carbon oxides (CO and CO₂) ware compared in order to determine the efficiency of the procedure.