NHTSA ID Number: 11006470
Manufacturer Communication Number: 20-NA-082
TSB/Document Date: 2024-08-16
Summary
This informational bulletin explains why more DEF is being used in diesel engines due to new emission standards.
Bulletin No.: 20-NA-082
Service Bulletin
Date: July, 2024
INFORMATION
Subject:
Brand:
Information on Excessive Diesel Exhaust Fluid (DEF) Usage
Model:
VIN:
to
Escalade Models
2021
2024
LM2
XT4
2020
2023
LSQ
Colorado
2020
2022
LWN
Express
2020
2022
LWN
Silverado 1500
2020
2021
LM2
Silverado 1500
2023
2025
LZ0
2022
2022
LM2
Silverado 2500HD/
3500HD
2020
2025
L5P
Silverado 4500HD,
5500HD, and
6500HD
2019
2025
L5D
Suburban
2021
2025
Tahoe
2021
2025
Canyon
2020
2022
LWN
Savana
2020
2022
LWN
Sierra 1500
2020
2021
LM2
Sierra 1500
2023
2025
LZ0
2022
2022
LM2
Sierra 2500/3500
2020
2025
L5P
Sierra 4500HD,
5500HD, and
6500HD
2019
2025
L5D
Yukon Models
2021
2025
LZ0
Silverado 1500 New
(RPO J22, VIN Digit
5 = A / D)
Sierra 1500 Limited
(RPO J21, VIN Digit
5 = 8 / 9)
Sierra 1500 New
(RPO J22, VIN Digit
5=H/U
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
Copyright 2024 General Motors. All Rights Reserved.
from
Engine:
from
Silverado 1500 LTD
(RPO J21, VIN Digit
5 = W / Y)
Chevrolet
Model Year:
to
LZ0
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.
Page 2
July, 2024
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, Europe
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
8
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.
Revised March 15, 2023 - Added 2024 Model Year for Silverado 2500/3500 and Sierra
2500/3500.
Revised March 20, 2023 - Added 2020-2023 XT4, (RPO LSQ)
Revised August 01, 2023 - Added 2024 Model Year for Silverado 1500 and Sierra 1500.
Revised July 31, 2024 – Updated Model Years to multiple models.
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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TSB/Document ID: 20-NA-082
Replacement Service Bulletin Number:
MFR Communication Date: 2024-07-31
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ENGINE
MFR Component System:
MFR Component Subsystem:
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