What is a Muffler? A muffler is the exhaust system of an engine, designed to reduce emissions and noise. In the case of a vehicle autel ms509, it is usually located underneath the car at the rear, though freighter trucks often use a vertically mounted system behind the cab. A muffler consists of a backbox and one or more tailpipes. When a vehicle is smogged, the inspector will insert a probe inside the tailpipe to read smog emissions emanating from the engine. A muffler helps to reduce the tremendous amount of noise that an engine produces. Although internal combustion accounts for some of this noise autel maxidiag elite md801, most of it comes from pressure waves generated by the rapid opening and closing of the engine's valves. The muffler's backbox is inte ... Read more »