For the turbocharger with a variable nozzle, the securing pin for the variable nozzle link may become worn out due to its insufficient abrasion resistance, and the position of the variable nozzle may change inadequately because of the slow response of the solenoid valve for that nozzle. These may increase exhaust flux , causing the turbine to over rotate. If left unfixed, the turbine blades may get damaged, making abnormal noises and causing insufficient power output, and in the worst case, shortage of intake air is caused, putting out black smoke exceeding the standard level.