2016 GMC Sierra engine problems

This Preliminary Information communication provides information to the technician on the steps to diagnose and repair vehicles that may have a Service Engine Soon Malfunction Indicator Lamp on at low mileage. Technician may find Diagnostic Trouble Codes P0420 and or P0430 stored. Technician should be advised that the catalytic converter efficiency Diagnostic Trouble Codes P0420 and P0430 are disabled for the first hour of engine run time to allow break-in of the catalytic converter. Technician will need to use a Tech2 to check the verify engine run time on the Engine Hour Meter in the Instrument Panel Cluster Data Display/Data 1 List in the scan tool match. If the engine run time is less tha

This engineering informational bulletin requests information from the field from vehicles that have the condition of a Check Engine Light, delayed shifts and/or the transmission stuck in gear.

THIS INFORMATIONAL BULLETIN PROVIDES THE TECHNICIAN WITH WHAT MAY HAPPEN TO AN ENGINE DUE TO LACK OF MAINTENANCE.

THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN ABOUT VEHICLE THAT MAY HAVE BLACK SMOKE ON A COLD START. A DUAL-PULSE INJECTION STRATEGY IS UTILIZED DURING ENGINE COLD START TO REDUCE THE TIME REQUIRED TO BRING THE CATALYTIC CONVERTER UP TO OPERATING TEMPERATURE. THIS SPLIT INJECTION STRATEGY LASTS FOR ABOUT 60 SECONDS ON COLD START. THIS PROCESS MAY CAUSE THE CUSTOMER TO SEE INCREASED BLACK SMOKE DURING COLD START AND SHOULD BE CONSIDERED NORMAL.

This informational bulletin provides information on close coupled converters and there affect on newly installed engines or engines during there break in period.