Carbon buildup occurs inside engines over time, reducing efficiency. There are two main methods to remove it: chemical decarbonization, which uses chemicals added to fuel to break up deposits, and physical decarbonization for severe cases, involving dismantling parts of the engine to manually clean them. Benefits of decarbonization include improved power, fuel efficiency, and emissions, as well as reduced noise and engine problems. It is generally recommended after 50,000 km to prevent excessive buildup.