20-NA-082

Bulletin No.:
Service Bulletin
Date:
20-NA-082
August, 2023
INFORMATION
Subject:
Brand:
Cadillac
Information on Excessive Diesel Exhaust Fluid (DEF) Usage
Model:
Escalade Models
2021
2023
VIN:
from
to
Engine:
LM2
XT4
2020
2023
LSQ
2020
2021
LWN
Express
2020
2022
LWN
Silverado 1500
2020
2021
LM2
Silverado 1500
2023
2024
LZ0
2022
2022
LM2
Silverado
2500HD/3500HD
2020
2024
L5P
Silverado 4500HD,
5500HD, and
6500HD
2019
2023
L5D
Suburban
2021
2023
Tahoe
2021
2023
Canyon
2020
2022
LWN
Savana
2020
2022
LWN
Sierra 1500
2020
2021
LM2
Sierra 1500
2023
2024
LZ0
2022
2022
LM2
Sierra 2500/3500
2020
2024
L5P
Sierra 4500HD,
5500HD, and
6500HD
2019
2023
L5D
Yukon Models
2021
2023
LM2
Silverado 1500
New (RPO J22,
VIN Digit 5 = A / D)
Sierra 1500 Limited
(RPO J21, VIN
Digit 5 = 8 / 9)
GMC
to
Colorado
Silverado 1500
LTD (RPO J21, VIN
Digit 5 = W / Y)
Chevrolet
Model Year:
from
Sierra 1500 New
(RPO J22, VIN
Digit 5 = H / U
Copyright 2023 General Motors LLC. All Rights Reserved.
LM2
Transmission:
Page 2
August, 2023
Bulletin No.: 20-NA-082
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.
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.
Bulletin No.: 20-NA-082
August, 2023
Page 3
Parts Information
No parts are required for this repair.
Version
7
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.
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.
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