On the 2006 and up 5.9L and 6.7L Cummins, the valve cover gasket is not only a gasket, but it also houses the injector wiring harness as well. In some cases, the harness can become damaged due to heat and being soaked in oil causing fuel injection issues. Whether your valve cover is leaking, or your harness is damaged, replace it with a Cummins Replacement Valve Cover Gasket With Harness. This is a direct replacement and features OEM style connectors and injector nuts.
TECH TIP:
If you are thinking your injector harness is bad, here is an easy way to test it. Remove the valve cover and unplug the injector harness at the two large connectors and each injector solenoid nut completely. Using an OHM meter, test the resistance of each wire from the large connector to each respective injector nut connection. If any wire measures over .05 OHMS, the wire is bad and the harness needs replacing.