Cataclean is a patented EPA approved complete engine, fuel and exhaust system cleaner that reduces carbon build-up and also cleans your vehicle's oxygen sensors, fuel injectors and cylinder heads. Cataclean does not alter fuel composition and is safe for gasoline, diesel and hybrid engines. Testing at an independent emissions testing facility showed using Cataclean can lower your total hydrocarbon emissions (Performance results are dependent on driver habits and vehicle condition.)