20-NA-166
Service Bulletin Details
Public Details for: 20-NA-166
This service bulletin advises the technician of possible coolant entering the areas of the engine, either through failed parts or defects in the castings, that may be the cause of the concerns related to the mil or the engine running rough.
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Bulletin No.: Service Bulletin Date: 20-NA-166 March, 2024 INFORMATION Subject: Information on Malfunction Indicator Lamp (MIL) Illuminated – DTCs P050D and/or P0300 Setting on a Cold Start and/or Engine Runs Rough when Warm with No Codes This Service Bulletin replaces PIP5498M. Please discard all versions of PIP5498. Brand: Cadillac Model: CTS 2016 2019 2015 2024 Camaro 2016 2024 Corvette 2016 2019 Silverado 2014 2018 Silverado 1500 (New Model) 2019 2019 2022 2022 2019 2019 2020 2021 Silverado 1500 New (RPO J22, VIN Digit 5 = A/D) Silverado LD Silverado 1500 Suburban 2023 2015 2024 Tahoe 2015 Sierra 2014 2018 Sierra 1500 (New Model) 2019 2019 2022 2022 2019 2019 2020 2021 Sierra 1500 Limited (RPO J21, VIN Digit 5 = 8/9) GMC to Escalade Silverado 1500 LTD (RPO J21, VIN Digit 5 = W/Y) Chevrolet Model Year: from Sierra 1500 New (RPO J22, VIN Digit 5 = H) Sierra Limited Sierra 1500 Yukon Models Copyright 2024 General Motors LLC. All Rights Reserved. 2023 2015 2024 VIN: from to — — Engine: Transmission: L82, L83, L86, L84, L87, LT1, LT4, LT5 — Page 2 March, 2024 Bulletin No.: 20-NA-166 Involved Region or Country North America, Argentina, Chile, Colombia, Ecuador, Venezuela, Europe, Russia, Middle East, Israel, Japan, Cadillac Korea (South Korea), China, Taiwan, Thailand, Singapore, Philippines, Other Africa, Australia/New Zealand Condition Some customers may comment on one or more of the following conditions: • The MIL is illuminated. • Engine runs rough when warm. Some technicians may find DTCs P050D and/or P0300 setting on a cold start. Cause This condition may be caused by coolant getting into the cylinders. Correction Validation will be required for possible internal coolant leaking into the cylinders. Refer to the Service Procedure below. 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. Service Procedure Technical Assistance (TAC) is currently receiving calls after the engine has been disassembled with no trouble found before completing SI diagnostics for DTC P0300 and P050D. Note: PLEASE BE SURE TO FIRST FOLLOW SI DIAGNOSTICS for P0300 and P050D THEN, IF DTC P050D FLOWCHART DOES NOT ISOLATE THE CONCERN, THEN THE FOLLOWING MAY BE HELPFUL: • Follow the flow chart for the P0300 to validate that there is not an ignition or mechanical concern with or without the P0300 set. • When completing the flow P050D chart, be sure you are checking the injector balance rates while the engine is cold. • Be sure to record the injector balance rates and attach to the work order. • If an injector concern is found, replace only the affected injector. Note: This will need to be done before the engine is disassembled. dual-pulse mode the ECM monitors the crankshaft position sensor and the camshaft position sensor to calculate crankshaft rotation speed. In normal operation, optimum fuel delivery during dual-pulse mode produces a steady crankshaft rotation speed. If the variations of crankshaft rotation speed exceed a calibrated value, the code P050D will be set. Misfires on start up only, with high rates always on one cylinder, can be suspect for coolant entry at the liner to deck face casting or the casting line in the intake port of the cylinder head. To inspect for this concern, add coolant dye to the system, run the engine through warm up, pressurize the cooling system after warming the engine to operating temperature (let the engine cool overnight) and inspect the suspect cylinder with a borescope for coolant dye evidence. At times it may be necessary to remove the head for inspection. If the head casting line is the concern, the intake port will be wet with a coolant oil mix. This could be the cause of a running rough warm concern with or without codes. The location of where the coolant is running down in the port will also look washed down. Note: If the injectors are being replaced on L86, LT1, LT4 or LT5, there are three different flow rate injectors offered. Be sure to install the same flow rate injectors back into the engine by checking the part number on the injector housing. Mixing the flow rates will cause driveability concerns, DTC setting and repeat injector replacements. Code P050D Description During a cold start, the engine control module (ECM) commands dual-pulse mode during Open Loop operation to improve cold start emissions. In dual-pulse mode, the fuel injectors are energized twice during each injection event. As with misfire diagnosis, in 4806659 If this is found, the cylinder head will need to be replaced. Bulletin No.: 20-NA-166 March, 2024 Page 3 4806657 It is also possible to have coolant entry at the liner to deck face casting of the cylinder bore (1). It is hard to see the actual source (pin hole), but it usually streams down the liner so that you can see it with a borescope. (Sometimes) The top of the piston will be steam cleaned. Do not confuse residual fuel on the piston crown / surface as coolant. Some fuel residue may be present and can be mistaken as coolant (reason for the cooling system Dye to be added). Use a black light to confirm the liquid is coolant. If this concern is present, do not replace the cylinder head because that will not repair this concern. Call the Product Quality Center (PQC) per Service Bulletins 20-NA-138 (U.S.) or 16-NA-338 (Canada), if required, reference this bulletin and replace the engine. Small surface pock marks or pitting appearance on the deck surface is normal and engines should not be replaced for such appearance as they do not connect to coolant passages and cause a leak path that generate engine misfires. During engine warranty analysis studies, engines are being replaced for small pitting in the deck face as described above, when the subject cylinder / piston is saturated with fuel and not coolant. Engines replaced for light / shallow pitting conditions will be returned to the dealership as non-defective. Parts Information No parts are required for this repair. Version 3 Modified Released August 21, 2020 Revised December 09, 2021 – Added the 2021-2022 Model Years and Australia/New Zealand to Involved Region or Country section. Revised March 21, 2024 – Added the 2023-2024 Model Years to applicable vehicles and the Important statement. 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