OBD System Software Upgrade-DTC P0128 Engine Coolant Temperature Below Thermostat Regulating Temperature (Reprogram Engine Control Module)

This bulletin provides information about installing new engine control module (ECM) calibration on certain 2003 vehicles equipped with the 6.6 liter Duramax® diesel engine. The revised calibration includes changes that allow for proper Malfunction Indicator Lamp (MIL) illumination when a P0128 DTC is stored. An updated calibration should be installed as soon as practical. Install the new calibration on all affected vehicles identified in this bulletin, including vehicles in new dealer inventory and any vehicles that return for service for any reason during the applicable 5 year 100,000 mile emission warranty coverage period. To verify if an updated calibration is required, refer to the following procedure in this bulletin.

Using A Tech 2 scan tool and TIS 2000, verify whether the calibration programmed into the vehicle’s ECM has been programmed with 15100899, 15100900 or later. The GM Vehicle Inquiry System (GM VIS) may be checked to see if the vehicle has been programmed since 15100899, 15100900 or the labor operation Y0001 has been claimed on the vehicle. If the 15100899, 15100900 or later updated calibration has not been installed or the Y0001 labor operation has not been claimed, reprogram the ECM with the latest updated calibration from TIS 2000 version 2.5 for 2003 data update or later.

For vehicles repaired under the applicable 5 year 100,000 mile emission warranty use: