The Rislone Cat Complete Fuel, Exhaust and Emissions System Cleaner, No. 4720, is an easy-to-install, cost-effective chemical solution to help customers pass emissions smog tests, turn off check engine lights, clear OBD codes, improve vehicle performance, and save gas. Simply add to half a tank of gas to clean the vehicle’s entire fuel, exhaust and emissions system. Cat Complete uses a proprietary blend of heavy duty detergents and solvents to remove contaminants, soot, carbon build-up, and oily residue from the fuel injectors, combustion chambers, turbo, catalytic converters, oxygen sensors, and exhaust.