20NA082

Service Bulletin
Bulletin No.:
20-NA-082
Date:
April, 2020
INFORMATION
Subject:
Brand:
Chevrolet
Information on Excessive Diesel Exhaust Fluid (DEF) Usage
Model:
VIN:
to
from
to
Engine:
Colorado
LWN
Express
LWN
Silverado
1500
LM2
Silverado
2500HD/
3500HD
L5P
Silverado
4500HD,
5500HD,
and 6500HD
GMC
Model Year:
from
Transmission:
L5D
2020
2020
Canyon
LWN
Savana
LWN
Sierra 1500
LM2
Sierra
2500/3500
L5P
Sierra
4500HD,
5500HD,
and 6500HD
L5D
Involved Region or Country
North America, Israel, Palestine, Chile (West), Paraguay (West), Uruguay (West)
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.
Copyright 2020 General Motors LLC. All Rights Reserved.
Page 2
April, 2020
Bulletin No.: 20-NA-082
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.
Parts Information
No parts are required for this repair.
Version
1
Modified
Released April 03, 2020
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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