Supersedes Technical Service Bulletin Group 17 number 15-64 dated June 3, 2015. A metallic whistling or grinding sound is heard from the engine compartment when the vehicle is at idle speed. The sound usually only occurs when the engine is warm. The MIL is sporadically on. DTCs are stored in the ECM. A leak in the crankcase breather module (pressure regulating valve) can cause this condition.