Hesitation, Roughness, Light Chuggle or Check Engine Light, DTC P0300 (Reprogram PCM)

Some customers may comment on a hesitation or engine roughness with or without the Check Engine Light illuminating. Upon investigation, the technician may or may not find code P0300, Random Misfire Detected. In some rare cases, the customer may comment on a light surge or fishbite when crowding the throttle with the TCC applied.

If a DTC code P0300 is set, follow the diagnostics in the appropriate Service Manual. If the diagnostics do not lead to a solution or if no DTC code is set, then reprogram the PCM. A new calibration has been released to address this concern. The following tables show the calibration number for reference, program the PCM with the appropriate listed calibration, or later, for this condition.

Important: Some 2004 vehicles may have a baffled style fuel tank per Corporate Bulletin Number 04-06-04-066. Check the Claim History in GM Vehicle Inquiry System to see if the fuel tank has been changed to a baffled style, P/N 15141578, since September 2004.

Additionally, the following nine vehicles were built with a baffled style fuel tank:

The new calibration will be released beginning with TIS satellite data update version 9.5 for 2004 available September 2004. As always, make sure your TECH2® is updated with the latest software version.

For vehicles repaired under the applicable 8 year or 80,000 mile (130,000 kilometres) emission controller warranty, use: