Identify Engine Misfiring and/or Malfunction Indicator Lamp (MIL) Illuminated – DTC P0300 Setting – 2017-2023 Chevrolet Silverado & GMC Sierra

SEOCONTENT-START

Copyright 2022 General Motors LLC. All Rights Reserved. Service Bulletin Bulletin No.: 19-NA-187 Date: September, 2022 INFORMATION Subject: Diagnostic Tip to Identify Engine Misfiring and/or Malfunction Indicator Lamp (MIL) Illuminated – DTC P0300 Setting Brand: Model: Model Year: VIN: Engine: Transmission: from to from to Chevrolet Silverado 2017 2018 Silverado L5P 2500/3500 2019 2023 Silverado 4500/5500/6500 2019 2023 L5D GMC Sierra 2017 2018 Sierra L5P 2500/3500 2019 2023 Involved Region or Country North America and Israel Condition Some customers may comment on one or more of the following conditions: • MIL illuminated • Engine misfire Some technicians may find DTC P0300 set in the Engine Control Module (ECM). Cause This condition may be caused by a weak cylinder. Correction Refer to the Service Procedure below to help identify which cylinder is misfiring. Service Procedure Important: Service agents must comply with all International, Federal, State, Provincial, and/or Local laws applicable to the activities it performs under this bulletin, including but not limited to handling, deploying, preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In the event of a conflict between the procedures set forth in this bulletin and the laws that apply to your dealership, you must follow those applicable laws. If there is any difficulty identifying a misfiring cylinder, it may be useful to graph the Cylinder Balance Test in GDS2. Do Not rely on this test as the ONLY means of identifying a weak cylinder. The balance test should only run when the misfire is present in the engine. Graph the engine RPM as well as each injector command. It is recommended to perform the test a minimum of three times with three different balance tests while looking for the consistency. The example below is from an engine that has a misfire on cylinder #1. It is recommend when setting up the graph, use the following settings: Page 2 September, 2022 Bulletin No.: 19-NA-187 5394634 The most important thing is that the RPM line is visible and not covered by the injector command lines. All three graphs below, each injector was cancelled in order, 1 – 8. 5394706 Note that cylinder #1 does not drop the RPM when canceled, when compared to the other cylinders. ⇒ RPM recovery is limited after the cancellation has ended. ⇒ Other cylinders do not have as much of a RPM drop when they are canceled, however the RPM does jump after the cancellation has ended. Bulletin No.: 19-NA-187 September, 2022 Page 3 5394746 During this second balance test, it appears like cylinder #1 is contributing, however it is less than any of the other cylinders. 5394869 During this final test, it appears that cylinder #5 is not contributing as well as #1. This is one of the main reasons that we must repeat the test to find consistency. ⇒ This vehicle was repaired by replacing #1 fuel injector. Note: This is not the only tool that should be used to identify a misfiring cylinder, but it can help aid in diagnosing this concern. Parts Information No parts are required for this repair. Page 4 September, 2022 Bulletin No.: 19-NA-187 Version 4 Modified Released August 23, 2019 Revised October 28, 2020 – Added 2021 Model Year. Revised January 12, 2022 – Added 2022 Model Year. Revised September 09, 2022 — Added the 2023 Model Year. GM bulletins are intended for use by professional technicians, NOT a “do-it-yourselfer”. They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information. WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

**************************************************************************************************************

**************************************************************************************************************

SEOCONTENT-END