Service Update - Certain vehicles, with a 6.6L diesel engine, have an Engine Control Module (ECM) that may not properly diagnose, may not set Diagnostic Trouble Codes (DTCs), or may not illuminate the Malfunction Indicator Light (Check Engine Light) if certain fault conditions of the Selective Catalyst Reduction (SCR or NOx) catalyst occur. Dealers are to reprogram the Engine Control Module (ECM) and Transmission Control Module (TCM).
