Chevrolet GMC Duramax 2023 User manual

C
M
Y
CM
MY
CY
CMY
K
ai166480313853_23_MUL_6.6L_Duramax_Diesel_Engine_SUP_COV_en_US_84883864 B_2022OCT10.pdf 1 10/3/2022 9:18:59 AM

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Contents
Introduction .............................. 1
Instruments and Controls . . . . . . . . . . . . . . . . . 3
Driving and Operating . . . . . . . . . . . . . . . . . . . 10
Vehicle Care ............................. 45
Service and Maintenance . . . . . . . . . . . . . . . . 60
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Introduction
The names, logos, emblems, slogans, vehicle
model names, and vehicle body designs
appearing in this manual including, but not
limited to, GM, the GM logo, CHEVROLET,
GMC, the CHEVROLET and GMC Truck
Emblems, SILVERADO, SIERRA, DENALI, and
Duramax are trademarks and/or service
marks of General Motors LLC, its
subsidiaries, affiliates, or licensors.
For vehicles first sold in Canada, substitute
the name “General Motors of Canada
Company”for GMC and Chevrolet Motor
Division wherever it appears in this manual.
This manual describes features that may or
may not be on the vehicle because of
optional equipment that was not purchased
on the vehicle, model variants, country
specifications, features/applications that may
not be available in your region, or changes
subsequent to the printing of this owner’s
manual, including changes in standard or
optional content.
Refer to the purchase documentation
relating to your specific vehicle to confirm
the features.
This manual contains information that
pertains to the operation of your diesel
engine. It also contains your Diesel
Maintenance Schedule. The sections in this
manual correspond to the sections in your
owner’s manual. This manual, along with
your owner’s manual, will assist you in the
proper use and maintenance of your vehicle.
Keep this manual in the vehicle for quick
reference.
Canadian Vehicle Owners
A French language manual can be obtained
from your dealer, at www.helminc.com,
or from:
Propriétaires Canadiens
On peut obtenir un exemplaire de ce guide
en français auprès du concessionnaire ou à
l'adresse suivante:
Helm, Incorporated
Attention: Customer Service
47911 Halyard Drive
Plymouth, MI 48170
USA
Litho in U.S.A.
Part No. 84883864 B Second Printing ©2022 General Motors LLC. All Rights Reserved.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
2 Introduction
Using this Supplement
This supplement contains information
specific to the unique components of the
vehicle. It does not explain everything you
need to know about the vehicle. Read this
supplement along with the owner’s manual
to learn about the vehicle's features and
controls.
Index
A good place to look for what you need is
the Index in the back of this supplement.
It is an alphabetical list of what is in the
supplement, and the page number where
you will find it.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Instruments and Controls 3
Instruments and Controls
Warning Lights, Gauges, and Indicators
Instrument Cluster . . . . . . . . . . . . . . . . . . . . . . . 3
Malfunction Indicator Lamp (Check Engine
Light) .................................. 6
Wait-to-Start Light . . . . . . . . . . . . . . . . . . . . . . . 7
Diesel Exhaust Fluid (DEF) Warning
Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Power Take-Off Light . . . . . . . . . . . . . . . . . . . . 8
Information Displays
Driver Information Center (DIC) . . . . . . . . . . 8
Warning Lights, Gauges, and Indicators
Instrument Cluster
Base Level Chevrolet English Cluster Shown, Metric Similar

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
4 Instruments and Controls
Base Level GMC English Cluster Shown, Metric Similar

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Instruments and Controls 5
Uplevel Chevrolet English Cluster Shown, Metric Similar

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
6 Instruments and Controls
Uplevel GMC English Cluster Shown, Metric Similar
Malfunction Indicator Lamp
(Check Engine Light)
This light is part of the vehicle’s emission
control on-board diagnostic system. If this
light is on while the engine is running, a
malfunction has been detected and the
vehicle may require service. The light should
come on to show that it is working when
the ignition is on with the engine not
running. See “Ignition Positions”in the
owner’s manual.
This light may also come on when the
system has detected a problem with the
Diesel Exhaust Fluid (DEF) management
system. See Diesel Exhaust Fluid 019.
Malfunctions are often indicated by the
system before any problem is noticeable.
Being aware of the light and seeking service
promptly when it comes on may prevent
damage.
Caution
If the vehicle is driven continually with
this light on, the emission control system
may not work as well, the fuel economy
may be lower, and the vehicle may not
run smoothly. This could lead to costly
repairs that might not be covered by the
vehicle warranty.
Caution
Modifications to the engine, transmission,
exhaust, intake, or fuel system, or the
use of replacement tires that do not
meet the original tire specifications, can
cause this light to come on. This could
(Continued)

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Instruments and Controls 7
Caution (Continued)
lead to costly repairs not covered by the
vehicle warranty. This could also affect
the vehicle’s ability to pass an Emissions
Inspection/Maintenance test. See
Accessories and Modifications 045.
When the light is on, a malfunction has
been detected. Diagnosis and service may be
required.
Poor fuel quality can cause inefficient engine
operation and poor driveability, which may
go away once the engine is warmed up.
If this occurs, change the fuel brand. It may
require at least one full tank of the proper
fuel to turn the light off. See Fuel for Diesel
Engines 023.
If the light remains on, see your dealer.
Emissions Inspection and Maintenance
Programs
If the vehicle requires an Emissions
Inspection/Maintenance test, the test
equipment will likely connect to the
vehicle's Data Link Connector (DLC).
The DLC is under the instrument panel to
the left of the steering wheel. Connecting
devices that are not used to perform an
Emissions Inspection/Maintenance test or to
service the vehicle may affect vehicle
operation. See “Add-On Electrical Equipment”
in the owner’s manual. See your dealer if
assistance is needed.
The vehicle may not pass inspection if:
.The light is on when the engine is
running.
.The light does not come on when the
ignition is on with the engine not
running.
.Critical emission control systems have not
been completely diagnosed. If this
happens, the vehicle would not be ready
for inspection and might require
several days of routine driving before the
system is ready for inspection. This can
happen if the 12-volt battery has recently
been replaced or run down, or if the
vehicle has recently been serviced.
See your dealer if the vehicle will not pass
or cannot be made ready for the test.
Wait-to-Start Light
This light comes on briefly while starting
the engine, as a check to show the light is
working.
If the wait-to-start light comes on, the glow
plug system is required and operating. Wait
until the light turns off before starting the
engine. This light may not come on in warm
temperatures.
The fast warm-up glow plug system makes
the wait-to-start light stay on for a shorter
amount of time than most diesel engines.
See Starting the Diesel Engine 010.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
8 Instruments and Controls
Diesel Exhaust Fluid (DEF)
Warning Light
This light, a Driver Information Center (DIC)
message, and a chime come on when there
is an issue with the Diesel Exhaust Fluid
system.
If the DEF issue has not been corrected, the
light will continue to flash when the vehicle
is started. The vehicle's speed may also be
limited.
See Diesel Exhaust Fluid 019.
Power Take-Off Light
Chassis Cab
The vehicle may have a Power Take-Off
(PTO) light. Under normal operating
conditions, the PTO light will remain on
throughout the PTO operating cycle. If all
conditions required to engage PTO have not
been met when enabling PTO, the PTO light
will turn on, then turn off after one second.
See Power Take-Off (PTO) 030.
Information Displays
Driver Information Center (DIC)
The DIC is in the instrument cluster. The DIC
comes on when the ignition is on.
A Duramax diesel vehicle may have the
following additional DIC menu items:
DEF : Displays the Diesel Exhaust Fluid (DEF)
level as a bar graph with individual
segments that illuminate from Empty (E) to
Full (F). When LOW appears on the display
and the segments turn red, add DEF as soon
as possible. For a guide on how much DEF
to add, see Diesel Exhaust Fluid 019.
Fuel Filter Life Remaining : This display
shows an estimate of the fuel filter's
remaining useful life. If 90% Fuel Filter Life
Remaining is displayed, it means 90% of the
current fuel filter life remains. The fuel filter
life system will alert when to change the
fuel filter on a schedule consistent with your
driving conditions.
When the remaining fuel filter life is low,
the CHANGE FUEL FILTER message will
appear on the display. Change the fuel filter
as soon as possible.
Fuel Filter Life Reset : Reset the Fuel Filter
Life Remaining display after each fuel filter
change. It will not reset itself. Also, be
careful not to reset the display at any time
other than when the fuel filter has just been
changed because it cannot be reset
accurately until the next fuel filter change.
The fuel filter life will change to 100% when
the system has been reset. To reset the
system, press and hold the thumbwheel for
two seconds while Fuel Filter Life Remaining
is displayed on the DIC.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Instruments and Controls 9
Engine Air Filter Life : Displays an estimate
of the engine air filter’s remaining useful life
and the state of the system. Engine Air
Filter Life 95% means 95% of the current air
filter life remains. Messages will display
based on the engine air filter life and the
state of the system. When the REPLACE AT
NEXT OIL CHANGE message displays, the
engine air filter should be replaced at the
time of the next oil change. When the
REPLACE SOON message displays, the engine
air filter should be replaced at the earliest
convenience. The Air Filter Life display must
be reset after the engine air filter
replacement. To reset, see Engine Air Filter
Life System 049.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
10 Driving and Operating
Driving and Operating
Starting and Operating
Starting the Diesel Engine . . . . . . . . . . . . . . 10
Winter Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Engine Heater . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Extended Parking . . . . . . . . . . . . . . . . . . . . . . . 16
Diesel Particulate Filter
Diesel Particulate Filter . . . . . . . . . . . . . . . . . 16
Diesel Exhaust Fluid
Diesel Exhaust Fluid . . . . . . . . . . . . . . . . . . . . 19
Brakes
Exhaust Brake . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Fuel
Top Tier Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Fuel Additives . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Fuel for Diesel Engines . . . . . . . . . . . . . . . . . 23
Biodiesel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Cold Weather Operation . . . . . . . . . . . . . . . . 24
Water in Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Running Out of Fuel . . . . . . . . . . . . . . . . . . . . 27
Fuel Filter Replacement . . . . . . . . . . . . . . . . . 27
Filling the Tank . . . . . . . . . . . . . . . . . . . . . . . . . 28
Filling a Portable Fuel Container . . . . . . . . 29
Trailer Towing
Trailer Towing . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Conversions and Add-Ons
Power Take-Off (PTO) . . . . . . . . . . . . . . . . . . . 30
Starting and Operating
Starting the Diesel Engine
The diesel engine starts differently than a
gasoline engine.
Caution
If the steering wheel is turned until it
reaches the end of its travel, and is held
in that position while starting the vehicle,
damage may occur to the hydraulic
power steering system and there may be
loss of power steering assist.
Move the shift lever to P (Park) or
N (Neutral). To restart the engine when the
vehicle is already moving, use
N (Neutral) only.
Caution
Do not try to shift to P (Park) if the
vehicle is moving. If you do, you could
damage the transmission. Shift to P (Park)
only when the vehicle is stopped.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Driving and Operating 11
Starting the Engine
Key Ignition Switch, if equipped
1. Turn the ignition key to ON/RUN.
Observe the wait-to-start light. See
Wait-to-Start Light 07. This light may
not come on if the engine is warm.
2. If the wait-to-start light is on, wait until
this light goes off. Turn the ignition key
to START, then release the ignition key.
The engine will continue to crank until
the engine starts.
The engine has a fast warm-up glow
plug system. The wait-to-start light will
illuminate for a much shorter time than
most diesel engines, due to the rapid
heating of the glow plug system.
Pushbutton Start, if equipped
1. Place your foot on the brake and press
ENGINE START/STOP.
Observe the wait-to-start light. See
Wait-to-Start Light 07. This light may
not come on if the engine is warm.
2. The wait-to-start light may be
illuminated, depending on temperature
conditions. There will be a delay in
engine cranking after pressing ENGINE
START/STOP based on temperature
conditions. In extremely cold
temperatures the delay will be longer. At
the end of the delay the engine will
begin to crank and will continue to crank
until the engine starts.
Caution
If the wait-to-start light stays on after
starting the vehicle, the vehicle may not
run properly. Have the vehicle serviced
right away.
If the engine does not start after 15 seconds
of cranking, turn the ignition off. Wait
one minute for the cranking motor to cool,
then try the same steps again.
If you are trying to start the engine after
you have run out of fuel, follow the steps in
Running Out of Fuel 027.
When the engine is cold, let it run for a few
minutes before driving. This lets oil pressure
build up. The engine will sound louder when
it is cold.
For turbo protection, engine power at
speeds above idle may be limited if the
engine is cold. This protection can last up to
40 seconds at extreme cold coolant and
ambient temperatures.
Cold Weather Starting
Use the recommended engine oil when the
outside temperature drops below freezing.
See Engine Oil 047. When the outside
temperature drops below –18 °C (0 °F), use
of the engine coolant heater is
recommended.
If you experience longer cranking times,
notice an unusual amount of exhaust smoke,
or are at higher elevations (over 2 135 m or
7,000 ft), you may use the engine coolant
heater. See Engine Heater 016.
See Fuel for Diesel Engines 023 for
information on what fuel to use in cold
weather.
If the Diesel Engine Will Not Start
If the vehicle runs out of fuel, see Running
Out of Fuel 027.
If the vehicle is not out of fuel, and the
engine will not start:
Place your foot on the brake and press
ENGINE START/STOP, if equipped.
Turn the ignition key, if equipped, to
ON/RUN. After the wait-to-start light goes
off, turn the ignition key to START.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
12 Driving and Operating
If the light does not go off, wait a few
seconds, then try starting the engine again.
See your dealer as soon as you can for a
starting system check.
If the light comes on and then goes off and
you know the batteries are charged, but the
engine still will not start, the vehicle needs
service.
If the light does not come on when the
engine is cold, the vehicle needs service.
If the batteries do not have enough charge
to start the engine, see “Battery”in the
owner’s manual.
Check that the correct engine oil has been
used and changed at appropriate intervals.
If the wrong oil is used, the engine may be
harder to start.
Be sure you are using the proper fuel for
existing weather conditions. See Fuel for
Diesel Engines 023.
If the engine starts, runs a short time, then
stops, the vehicle needs service.
{Warning
Do not use gasoline or starting aids, such
as ether, in the air intake. They could
damage the engine, which may not be
covered by the vehicle warranty. They
could also cause a fire, which could cause
serious personal injury.
Engine Idle Variations
Under certain conditions the engine idle
speed can vary or be elevated. Change in
idle speed is normal and does not indicate a
problem. Normal conditions that can raise
idle speed are low voltage, DPF
regeneration, air conditioning compressor
loads, and engine warmup. These speeds can
range from approximately 600 to 1000 rpm.
Elevated Idle
The engine has a cold temperature high idle
feature which elevates the engine idle speed
from base idle to 1050 to 1100 rpm when
outside temperatures are below 0 °C (32 °F),
and the engine coolant temperature is
below 65 °C (150 °F). This feature enhances
heater performance by raising the engine
coolant temperature faster.
To enable or disable Elevated Idle, select
Settings > Vehicle > Climate and Air
Quality > Rapid Heat-Elevated Idle > ON
or OFF.
When the engine is started, it will slowly
ramp up to the high idle speed after a delay
of a few seconds up to approximately
two minutes. For this method to work
properly there must be no throttle or brake
pedal faults.
The engine idle speed will return to normal
once the following conditions are met:
.Engine coolant temperature reaches 65 °C
(150 °F).
.Air intake temperature reaches 0 °C
(32 °F).
The high idle speed will be temporarily
interrupted and the engine speed will return
to normal if any of the following conditions
occur:
.The brake pedal is applied.
.The accelerator pedal is pressed.
.The transmission is shifted out of P (Park)
or N (Neutral).
.Vehicle speed is detected.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Driving and Operating 13
Once these inputs are removed, the engine
idle speed will slowly ramp back up to high
idle after the normal delay, if the conditions
for engine coolant temperature and air
intake temperature are still met.
Fast Idle Control
If equipped, this system can be used to
increase the engine idle speed.
Fast Idle control will be enabled when the
following conditions are met:
.The parking brake is set.
.The transmission is in P (Park) or
N (Neutral).
.The vehicle speed is about
0 km/h (0 mph).
.The cruise control Set switch is pressed
and released for Preset Fast Idle Speed
(1200 rpm).
Fast Idle control will be disabled when one
or more of the following conditions occur:
.The cruise control Set switch is pressed
and released. See “Cruise Control”in the
owner’s manual.
.The cruise control Cancel switch is
pressed.
.The brake pedal is pressed.
.The transmission is shifted out of P (Park)
or N (Neutral).
.The parking brake is released.
.The vehicle speed is not 0 km/h (0 mph).
Winter Cover
If equipped, the winter cover should be used
to enhance heater performance in cold
conditions below -5 °C (23 °F). The winter
cover installs over the grille and restricts
airflow to the engine compartment.
For vehicles that did not come with a winter
cover, a GM winter cover can be purchased.
See your dealer for additional information.
When the winter cover is in use, the heater,
ventilation, and air conditioning AUTO mode
may not function properly. Use the manual
settings for comfort.
Usage Guidelines
The winter cover should only be used while
operating the vehicle in cold temperatures
or in heavy snow. In these temperatures,
the vehicle does not need a large amount of
air to properly cool the engine. When more
airflow is required to cool the vehicle, the
winter cover should not be used. The
following usage guidelines will allow
adequate airflow for proper radiator and air
cooler performance:
.Do not use the winter cover if towing a
trailer in conditions above 0 °C (32 °F). The
vehicle may overheat if the radiator is
covered while towing.
.Do not use the winter cover if a snow
plow is mounted on the truck.
.Do not cover the opening in the front
bumper.
.Do not modify the cover. The winter
cover does not cover some sections of the
front of the vehicle to provide enough
airflow.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
14 Driving and Operating
.When the winter cover is used, the
outside air temperature display may not
function properly.
.Keep the underside of the winter cover as
clean as possible. Remove monthly or as
necessary and clean away dust and
debris.
.Use only a mild soap to clean. Do not use
harsh soap, strong detergents, or vinyl
protectant/sealant type products as they
may damage the special finish. Allow the
winter cover to dry completely before
reinstalling.
Installation Instructions
When first trying to fit the cover, it may
appear to be undersized but will stretch
during installation to ensure a tight fit. The
initial installation of the cover is best
performed when the winter cover is warm.
Installation (Chevrolet Pickup)
1. The white label must be at the top and
back of the cover.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Driving and Operating 15
2. Starting in the middle, attach fastening
points as illustrated.
3. To remove, reverse the steps listed
previously.
Installation (GMC Pickup)
1. The white label must be at the top and
back of the cover.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
16 Driving and Operating
2. Starting in the middle, attach fastening
points as illustrated.
3. To remove, reverse the steps listed
previously.
Engine Heater
{Warning
Do not plug in the engine block heater
while the vehicle is parked in a garage or
under a carport. Property damage or
personal injury may result. Always park
the vehicle in a clear open area away
from buildings or structures.
If equipped, the engine heater can provide
easier starting in cold weather conditions at
or below −18 °C (0 °F).
For engine heater operation, see “Engine
Heater”in the owner’s manual.
Extended Parking
This vehicle is not equipped with an
automatic engine shutdown feature.
Diesel Particulate Filter
The exhaust system has a Diesel Particulate
Filter (DPF) to reduce vehicle emissions. On
some exhaust systems with a DPF, the
exhaust cooler mixes air with the exhaust to
lower the temperature before it leaves the
tailpipe.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Driving and Operating 17
The DPF, the tailpipe, and other exhaust
system components must not be altered.
Inspect regularly and clean any mud or dirt
from the exhaust cooler, especially where
the exhaust cooler connects to the tailpipe
and the openings where fresh air enters the
cooler.
The DPF will clean itself as part of normal
operation. Several factors including fuel
consumed, hours of engine operation, and
miles driven are monitored by the Engine
Control Module (ECM). The self-cleaning
occurs approximately once per tank of fuel.
Vehicles with the DPF have specific fuel and
engine oil requirements. See Fuel for Diesel
Engines 023 and
Engine Oil 047.
Caution
Damage can occur to the DPF
components if the required Ultra Low
Sulfur Diesel (15 ppm sulfur maximum)
fuel and engine oil specified in the
Recommended Fluids and Lubricants
section of this manual are not used. This
damage would not be covered by the
vehicle warranty.
Under certain conditions, such as idling or
very short trips, the self-cleaning process has
less efficiency and cannot be completed.
To resolve this, continue driving safely at a
steady speed as close to the posted speed
limit as possible, preferably without
stopping, until the message turns off. This
can take up to 30 minutes.
{Warning
During DPF self cleaning or during
extended idling in P (Park), the exhaust
system and exhaust gases are very hot.
Things that burn could touch hot exhaust
parts under the vehicle and ignite. You or
others could be burned. Do not park,
or idle for an extended period of time,
near or over papers, leaves, dry grass,
or other things that can burn. Keep the
exhaust area clear of material that could
ignite or burn. See “Parking over Things
That Burn”in the owner’s manual.
Caution
Avoid extended idling because the DPF
system is not capable of self-cleaning at
idle. During extended idling, monitor the
instrument cluster lights and DIC for
messages and take appropriate action.
Continued idling with the warning light/
message on could cause damage to the
DPF requiring repair and possible
replacement that might not be covered
by the vehicle warranty.
During self-cleaning there will be a change
in the exhaust sound and engine idle speed.
Along with this, a burning smell and
reduction in fuel economy may be noticed.
This is normal.
If the vehicle is idled or driven on very short
trips with the DPF warning message on and
the exhaust filter is not cleaned as required,
the malfunction indicator lamp and a DIC
message will display. See your dealer. Also
see Malfunction Indicator Lamp (Check
Engine Light) 06.
See Accessories and Modifications 045 if
you are adding accessories or modifying the
vehicle.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
18 Driving and Operating
Manual Regeneration of Diesel
Particulate Filter
This feature is only available on Fleet and
Commercial vehicles.
To verify that the vehicle has this feature,
refer to the Vehicle Service Parts
Identification label (SPID) for RPO code FPF
or see www.gmupfitter.com to contact the
GM Upfitter Integration Group.
If equipped, this feature allows for manual
cleaning/regeneration of the DPF when it is
unable to clean itself. It may be necessary
to perform manual regeneration if driving
conditions —such as extended slow speed,
stop-and-go traffic, extended idling, short
drive cycles, or stationary PTO operation —
prevent DPF self-cleaning.
Manual regeneration can only be used on
most vehicles when the DPF has become at
least 90% full. At 100% full, it will attempt
to automatically self-clean if proper driving
conditions are met. The DPF will clean itself
if the vehicle can be driven for about
30 minutes.
A DIC message displays when manual
regeneration is possible.
Scroll through the DIC pages to find the
Exhaust Cleaning menu. Depending on
whether the vehicle has a base or uplevel
cluster, it may be under the Settings menu.
If the vehicle cannot be stopped when the
DIC message first indicates cleaning is
available, automatic self-cleaning may have
begun. If conditions cannot be met for
self-cleaning to complete, and manual
regeneration is selected, it may take up to
four minutes for the system to switch to
manual regeneration. When the switch
occurs, a DIC message prompts to start the
cleaning process.
{Warning
Do not leave the vehicle during the
regeneration.
Make sure that there are no flammable
materials near the muffler, DPF, and
exhaust pipe which may result in a fire.
The temperature of exhaust gases is high
enough to burn you. You and others
could be seriously injured.
Before starting manual regeneration, make
sure all of the following safety conditions
are met:
.The vehicle is parked on level ground,
away from any flammable materials.
.The vehicle is parked outdoors, away
from any walls or buildings.
.The vehicle is at least 3 m (10 ft) from
any obstructions or materials that may
combust or melt.
.The shift lever is in P (Park).
.The fuel tank is at least one-eighth full.
.All fluids are at the proper level.
.No diagnostic trouble codes have been
set, and the malfunction indicator lamp is
not on.
.The engine coolant temperature is above
71 °C (160 °F).
After making sure all safety conditions have
been met, press the trip odometer reset
stem or thumbwheel on the steering wheel
for at least one second to select Start on
the infotainment display.
Follow the instructions in the DIC messages.
Touch ACCEPT to acknowledge that all of
these safety conditions have been met and
to activate regeneration.

Chevrolet/GMC 6.6L Duramax Diesel Engine Supplement (GMNA-Localizing-
U.S./Canada-16504481) - 2023 - CRC - 9/26/22
Driving and Operating 19
If the infotainment display returns to the
previous screen, then one or more of the
necessary safety conditions has not been
met. If you cannot determine which
condition has not been met, see
www.gmupfitter.com to contact the GM
Upfitter Integration Group.
Continue to follow the instructions in the
DIC messages. Hold the exhaust brake
switch on the center stack below the climate
controls for more than three seconds, and
then release it, to begin the regeneration
process.
If the EXHAUST BRAKE ON message displays,
then the switch was released too soon.
Press it again to turn off the exhaust brake,
then try again when the DIC message
prompts.
When manual regeneration begins, the
engine speed increases, the engine cooling
fan sound increases, and a DIC message
indicates that cleaning is in progress.
A DIC message will display when cleaning is
complete. Cleaning could take up to
30 minutes. Upon completion, the engine
will return to normal idle, but exhaust
components will remain hot for several
minutes. Do not move the vehicle until the
exhaust has had time to cool. Manual
regeneration can be canceled at any time by
pressing the brake pedal or by turning the
engine off. Unusual noises may be heard if
regeneration is interrupted.
Diesel Exhaust Fluid
{Warning
Avoid getting Diesel Exhaust Fluid (DEF)
on your skin or in your eyes as it could
cause irritation. For more safety,
handling, and storage information, see
the Diesel Exhaust Fluid container label.
Caution
Use only DEF that is GM approved,
or fluid containing the API certified or ISO
22241 label. The use of other fluids could
damage the system, requiring costly
repairs that will not be covered by the
vehicle warranty.
Caution
Do not mix fuel with DEF, and do not put
DEF in the fuel tank. This could lead to
costly repairs that might not be covered
by the vehicle warranty.
Diesel Exhaust Fluid (DEF) is used with diesel
engines to reduce the amount of regulated
emissions produced. Products such as AdBlue
are types of DEF. The fluid level in the DEF
tank must be maintained for the vehicle to
run properly. DEF is not a fuel additive. DEF
freezes when exposed to temperatures
below −11 °C (12 °F). For DEF tank capacity
see Capacities and Specifications 066.
It is normal to hear the DEF system purge
fluid back into the tank after the vehicle is
shut off.
Locating Diesel Exhaust Fluid
DEF can be purchased at your authorized
dealers. Additionally, some diesel truck
fueling stations or retailers may have DEF
for purchase. For vehicles with an active
OnStar or connected services plan, OnStar
can help to locate a DEF retailer. See
“Customer Assistance Offices”in the owner’s