Despite the many advantages of the 5.9 Cummins injectors, it has disadvantages as well. 5.9 Cummins injectors just like any other machine experience wear and tear among several other problems. The most challenging thing of the 5.9 Cummins injectors is mainly the repairing and the diagnosis of a problem. You mainly require a good mechanic to analyze a problem as cases of misdiagnosis can occur. Below are some of the problems of the 5.9 Cummins Injectors.