many consumers will find themselves to buy a new car, ran a high-speed driving or some time in the future, there will be some black and gray in the vent position, for some of these will be defined smudge master fault, but some master would say this is an occasional car will appear the situation, do not worry about, then what is it because of what this phenomenon, it is a failure?
Non-Fault: impurities during vehicle assembly line in the high-temperature exhaust gas discharged
There are certain engine cleanliness requirements during assembly, the exhaust line and a three-way catalyst or will be mixed with a content of carbon, which makes the initial ignition engine car or a later time, such as a high temperature grease inner wall of the engine exhaust line of the inner wall and other impurities, such as iron, etc. oxidation at high temperatures to form black and gray, and with the exhaust gas is discharged outside the vehicle.
