Information on Excessive Diesel Exhaust Fluid (DEF) Usage – 2019-2023 Cadillac Chevrolet GMC

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Copyright 2022 General Motors LLC. All Rights Reserved. Service Bulletin Bulletin No.: 20-NA-082 Date: September, 2022 INFORMATION Subject: Information on Excessive Diesel Exhaust Fluid (DEF) Usage Brand: Model: Model Year: VIN: Engine: Transmission: from to from to Cadillac Escalade Models 2021 2023 LM2 Chevrolet Colorado 2020 2021 LWN Express 2020 2022 LWN Silverado 1500 2020 2021 LM2 Silverado 1500 2023 2023 LZ0 Silverado 1500 LTD (RPO J21, VIN Digit 5 = W / Y) Silverado 1500 New (RPO J22, VIN Digit 5 = A / D) 2022 2022 LM2 Silverado 2500HD/ 3500HD 2020 2023 L5P Silverado 4500HD, 5500HD, and 6500HD 2019 2023 L5D Suburban 2021 2023 LM2 Tahoe 2021 2023 GMC Canyon 2020 2022 LWN Savana 2020 2022 LWN Sierra 1500 2020 2021 LM2 Sierra 1500 2023 2023 LZ0 Sierra 1500 Limited (RPO J21, VIN Digit 5 = 8 / 9) Sierra 1500 New (RPO J22, VIN Digit 5 = H / U 2022 2022 LM2 Sierra 2500/3500 2020 2023 L5P Sierra 4500HD, 5500HD, and 6500HD 2019 2023 L5D Yukon Models 2021 2023 LM2 Page 2 September, 2022 Bulletin No.: 20-NA-082 Involved Region or Country North America, Uzbekistan, Russia, Middle East, Israel, Palestine, Bolivia (West), Chile (West), Colombia (West), Ecuador (West), Paraguay (West), Peru (West), Uruguay (West), Japan, Cadillac Korea (South Korea), GM Korea Company, Thailand Condition Some customers may comment that excessive DEF is being used. Some technicians may find no codes set or messages on the DIC. Information The current 2020 Silverado/Sierra is the first to have a DEF level gauge on the IP. This is the first time a customer can see a representation of how much DEF is in the tank up to the full capacity of the tank. This gauge does not operate like the float style gauge that you have in your fuel tank. Because of this, you may see some fluctuation in the gauge. It may also take a few key cycles to register the correct amount in the tank after a fill event. With the new segmented DEF level gauge, it is possible that after adding 5 gallons (18.9 L) of DEF that the gauge reads as a full tank after the fill event. However, if the actual level of DEF is just entering the last segment on the gauge, the gauge is likely to drop by one segment shortly after driving after the fill event. This could give an initial impression that the vehicle consumes a lot of DEF. Every year that GM produces vehicles with diesel engines, the requirements to reduce Nitrogen Oxides (NOx) in the vehicle exhaust continue to get more aggressive. Because DEF is required to reduce the NOx in the exhaust, DEF consumption will increase as NOx reduction requirements increase. When customers trade in an older model year diesel Silverado/Sierra for a newer model year, there will likely be an increase in DEF usage. DEF consumption increases as the newer vehicles meet the more stringent emission requirements for that model year. The amount of DEF usage is also a function of how hard the engine is working, or engine load. Because of this, it is more representative to compare DEF usage to the amount of fuel used, also a function of engine load, instead of miles traveled. In addition to engine load, other factors that affect the DEF usage rate are the humidity, temperature, and altitude where the vehicle is operating. Under certain conditions, the ECM will increase or decrease the amount of DEF used based on learning or adaptive algorithms. In the event of a malfunction and SES light, the ECM may double or even eliminate the amount of DEF that is being used. This will continue until the vehicle is repaired and until the learned value in the ECM is reset. When towing a trailer or when the vehicle is heavily loaded, the vehicle will use more DEF per mile. While the DEF usage at any one moment is calculated instantaneously based on the amount of NOx the engine produces, the average DEF consumed takes much longer to adjust down after the heavy load is removed from the vehicle. When a customer sees a message stating XXX miles to empty, this is based roughly on the average amount of DEF used. If the vehicle is heavily loaded during that XXX miles, the range will be lower. Conversely if the vehicle is not heavily loaded, the range will be more than XXX. For some customer usage scenarios, this can give the impression that the vehicle is using too much DEF when in actuality if you measure the amount of DEF consumed based on fuel consumption you will get a much more accurate measurement. Parts Information No parts are required for this repair. Version 4 Modified Released April 03, 2020 Revised March 10, 2021 – Added 2021 to Model Year. Revised February 03, 2022 – Added 2022 and Towing Information in the Information section. Revised September 12, 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

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