2020 GMC SIERRA check engine light

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
322 Driving and Operating
reminder will appear to turn on Tow/
Haul Mode when the Trailer Profile
is active.
If Tow/Haul Mode is on and this
setting is on for a Trailer Profile, the
reminder will not appear when the
Trailer Profile is active.Conversions and
Add-Ons
Add-On Electrical
Equipment
{Warning
The Data Link Connector (DLC) is
used for vehicle service and
Emission Inspection/Maintenance
testing. SeeMalfunction Indicator
Lamp (Check Engine Light) 0138
. A device connected to the DLC
— such as an aftermarket fleet or
driver-behavior tracking device —
may interfere with vehicle
systems. This could affect vehicle
operation and cause a crash.
Such devices may also access
information stored in the vehicle’s
systems.
Caution
Some electrical equipment can
damage the vehicle or cause
components to not work and
would not be covered by the
vehicle warranty. Always check
with your dealer before adding
electrical equipment.
Add-on equipment can drain the
vehicle's 12-volt battery, even if the
vehicle is not operating.
The vehicle has an airbag system.
Before attempting to add anything
electrical to the vehicle, see
Servicing the Airbag-Equipped
Vehicle 083 and
Adding Equipment to the
Airbag-Equipped Vehicle 083.
For information on wiring auxiliary
switches, see www.gmupfitter.com
or contact your dealer.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
Vehicle Care 327
Vehicle Care
General Information
General Information . . . . . . . . . . 328
California Proposition65 Warning . . . . . . . . . . . . . . . . . 329
California Perchlorate Materials Requirements . . . . . 329
Accessories and Modifications . . . . . . . . . . . . . . . . 329
Vehicle Checks
Doing Your OwnService Work . . . . . . . . . . . . . . . 330
Hood . . . . . . . . . . . . . . . . . . . . . . . . . 330
Engine Compartment Overview . . . . . . . . . . . . . . . . . . . . 332
Engine Oil . . . . . . . . . . . . . . . . . . . . 339
Engine Oil Life System . . . . . . . 341
Automatic Transmission Fluid . . . . . . . . . . . . . . . . . . . . . . . . 343
Engine Air Filter Life System . . . . . . . . . . . . . . . . . . . . . . 343
Engine Air Cleaner/Filter . . . . . . 344
Cooling System . . . . . . . . . . . . . . 346
Engine Overheating . . . . . . . . . . 351
Overheated Engine Protection Operating Mode . . . . . . . . . . . . . 352
Engine Fan . . . . . . . . . . . . . . . . . . . 353 Power Steering Fluid . . . . . . . . . 354
Washer Fluid . . . . . . . . . . . . . . . . . 354
Brakes . . . . . . . . . . . . . . . . . . . . . . . 355
Brake Pad Life System . . . . . . . 356
Brake Fluid . . . . . . . . . . . . . . . . . . . 357
Battery - North America . . . . . . 358
Four-Wheel Drive . . . . . . . . . . . . . 361
Front Axle . . . . . . . . . . . . . . . . . . . . 361
Rear Axle . . . . . . . . . . . . . . . . . . . . 362
Noise Control System . . . . . . . . 362
Starter Switch Check . . . . . . . . . 363
Automatic Transmission Shift
Lock Control Function
Check . . . . . . . . . . . . . . . . . . . . . . . 363
Ignition Transmission Lock Check . . . . . . . . . . . . . . . . . . . . . . . 363
Park Brake and P (Park) Mechanism Check . . . . . . . . . . 364
Wiper Blade Replacement . . . . 364
Windshield Replacement . . . . . 365
Gas Strut(s) . . . . . . . . . . . . . . . . . . 365
Headlamp Aiming
Headlamp Aiming . . . . . . . . . . . . 366
Bulb Replacement
Bulb Replacement . . . . . . . . . . . . 367
Halogen Bulbs . . . . . . . . . . . . . . . . 367
LED Lighting . . . . . . . . . . . . . . . . . 367 Headlamps, Front Turn Signal,
Sidemarker, and Parking
Lamps . . . . . . . . . . . . . . . . . . . . . . 367
Taillamps, Turn Signal, Stoplamps, and Back-Up
Lamps . . . . . . . . . . . . . . . . . . . . . . 368
Center High-Mounted Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 369
License Plate Lamp . . . . . . . . . . 369
Electrical System
Electrical System Overload . . . 370
Fuses and Circuit Breakers . . . 370
Engine Compartment Fuse Block . . . . . . . . . . . . . . . . . . . . . . . . 371
Instrument Panel Fuse
Block (Left) . . . . . . . . . . . . . . . . . 374
Instrument Panel Fuse Block (Right) . . . . . . . . . . . . . . . . . . . . . . 376
Wheels and Tires
Tires . . . . . . . . . . . . . . . . . . . . . . . . . . 379
All-Season Tires . . . . . . . . . . . . . . 379
Winter Tires . . . . . . . . . . . . . . . . . . 380
Low-Profile Tires . . . . . . . . . . . . . 380
All-Terrain Tires . . . . . . . . . . . . . . . 381
Tire Sidewall Labeling . . . . . . . . 381
Tire Designations . . . . . . . . . . . . . 383
Tire Terminology andDefinitions . . . . . . . . . . . . . . . . . . 385

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/10/19
428 Vehicle Care
light in the instrument cluster
will stop flashing and stay lit.
SeeFour-Wheel-Drive Light
0 142.
8. Start the engine. Check that the vehicle is in 2
m
(Two-Wheel Drive High) by
starting the engine and shifting
the transmission to D (Drive)
and then to R (Reverse). There
should be movement of the
vehicle while shifting.
9. Shift the transmission to P (Park) and turn off the
ignition.
10. Release the parking brake and remove the wheel blocks.
11. Reset any lost presets. The outside temperature
display will default to 0 °C (32 °
F) but will reset with normal
usage.
Dolly TowingCaution
Do not tow this vehicle with two
wheels on the ground, or vehicle
damage could occur. This
damage would not be covered by
the vehicle warranty.
Dolly towing this vehicle is not
allowed with either the front or the
rear tires on the ground for
two-wheel drive or four-wheel drive,
regardless of transfer case.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/
Mexico-13337776) - 2020 - CRC - 4/4/19
450 Service and Maintenance
Additional
Maintenance and Care
Your vehicle is an important
investment and caring for it properly
may help to avoid future costly
repairs. To maintain vehicle
performance, additional
maintenance services may be
required.
It is recommended that your dealer
perform these services—their
trained dealer technicians know
your vehicle best. Your dealer can
also perform a thorough
assessment with a multi-point
inspection to recommend when your
vehicle may need attention.
The following list is intended to
explain the services and conditions
to look for that may indicate
services are required.
Battery
The 12-volt battery supplies power
to start the engine and operate any
additional electrical accessories. .
To avoid break-down or failure to
start the vehicle, maintain a
battery with full cranking power.
. Trained dealer technicians have
the diagnostic equipment to test
the battery and ensure that the
connections and cables are
corrosion-free.
Belts
. Belts may need replacing if they
squeak or show signs of
cracking or splitting.
. Trained dealer technicians have
access to tools and equipment
to inspect the belts and
recommend adjustment or
replacement when necessary.
Brakes
Brakes stop the vehicle and are
crucial to safe driving.
. Signs of brake wear may include
chirping, grinding, or squealing
noises, or difficulty stopping. .
Trained dealer technicians have
access to tools and equipment
to inspect the brakes and
recommend quality parts
engineered for the vehicle.
Fluids
Proper fluid levels and approved
fluids protect the vehicle’s systems
and components. See
Recommended Fluids and
Lubricants 0453 for GM approved
fluids.
. Engine oil and windshield
washer fluid levels should be
checked at every fuel fill.
. Instrument cluster lights may
come on to indicate that fluids
may be low and need to be
filled.
Hoses
Hoses transport fluids and should
be regularly inspected to ensure
that there are no cracks or leaks.
With a multi-point inspection, your
dealer can inspect the hoses and
advise if replacement is needed.

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/-
Mexico-13337776) - 2020 - CRC - 4/4/19
488 Index
IndexA
Accessories andModifications . . . . . . . . . . . . . . . . . . 329
Accessory Power . . . . . . . . . . . . . . . 217
Active Fuel Management . . . . . . . 219
Adaptive Cruise Control . . . . . . . . 245
Add-On Electrical Equipment . . . 322
Adding a Snow Plow or Similar Equipment . . . . . . . . . . . . . 323
Additional Information
OnStar . . . . . . . . . . . . . . . . . . . . . . . 479
Additional Maintenance and Care . . . . . . . . . . . . . . . . . . . . . . 450
Adjustments
Lumbar, Front Seats . . . . . . . . . . . . 57
Air Cleaner/Filter, Engine . . . . . . . 344
Air Conditioning . . . . . . . . . . . 177, 179
Air Filter Life System . . . . . . . . . . . . . . . . . . . 343
Air Filter, Passenger Compartment . . . . . . . . . . . . . . . . . 183
Air Vents . . . . . . . . . . . . . . . . . . . . . . . 182
Airbag System Check . . . . . . . . . . . . . . . . . . . . . . . . . . 84
How Does an Airbag
Restrain? . . . . . . . . . . . . . . . . . . . . . 77
Passenger Sensing System . . . . 78 Airbag System (cont'd)
What Makes an Airbag
Inflate? . . . . . . . . . . . . . . . . . . . . . . . . 76
What Will You See after an
Airbag Inflates? . . . . . . . . . . . . . . . 77
When Should an Airbag Inflate? . . . . . . . . . . . . . . . . . . . . . . . . 76
Where Are the Airbags? . . . . . . . . 74
Airbags
Adding Equipment to theVehicle . . . . . . . . . . . . . . . . . . . . . . . . 83
Passenger Status Indicator . . . 137
Readiness Light . . . . . . . . . . . . . . 136
Servicing Airbag-Equipped Vehicles . . . . . . . . . . . . . . . . . . . . . . . 83
System Check . . . . . . . . . . . . . . . . . . 72
Alarm Vehicle Security . . . . . . . . . . . . . . . . 37
Alert Lane Change . . . . . . . . . . . . . . . . . 274
Side Blind Zone (SBZA) . . . . . . 274
All-Season Tires . . . . . . . . . . . . . . . . 379
All-Terrain Tires . . . . . . . . . . . . . . . . . 381
Antilock Brake System (ABS) . . . 232 Warning Light . . . . . . . . . . . . . . . . . 141
Appearance Care Exterior . . . . . . . . . . . . . . . . . . . . . . . 429
Interior . . . . . . . . . . . . . . . . . . . . . . . . 435

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/-
Mexico-13337776) - 2020 - CRC - 4/4/19
Index 489
Assistance Program,Roadside . . . . . . . . . . . . . . . . . . . . . . 467
Assistance Systems for Driving . . . . . . . . . . . . . . . . . . . . . . . . 268
Assistance Systems for Parking and Backing . . . . . . . . . . 257
Auto Stop
Stop/Start System . . . . . . . . . . . . 213
Automatic Dimming Mirrors . . . . . . . . . . . . . . . . 44
Door Locks . . . . . . . . . . . . . . . . . . . . . 26
Emergency Braking (AEB) . . . . 270
Headlamp System . . . . . . . . . . . . 168
Transmission . . . . . . . . . . . . . . . . . 221
Transmission Fluid . . . . . . . . . . . 343
Automatic Transmission
Manual Mode . . . . . . . . . . . . . . . . . 224
Shift Lock Control FunctionCheck . . . . . . . . . . . . . . . . . . . . . . . 363
Axle, Front . . . . . . . . . . . . . . . . . . . . . . 361
Axle, Rear . . . . . . . . . . . . . . . . . . . . . . 362
B
Battery Exterior Lighting BatterySaver . . . . . . . . . . . . . . . . . . . . . . . 174
Load Management . . . . . . . . . . . . 174 Battery (cont'd)
Power Protection . . . . . . . . . . . . . 174
Battery - North America . . . . 358, 419
Blade Replacement, Wiper . . . . . 364
Blind Spot Mirrors . . . . . . . . . . . . . . . 44
Brake Electric Boost . . . . . . . . . . . . . . . . . 232
Parking, Electric . . . . . . . . . . . . . . 233
System Warning Light . . . . . . . . 140
Brake Pad Life System . . . . . . . . . 356
Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . 355 Antilock . . . . . . . . . . . . . . . . . . . . . . . 232
Assist . . . . . . . . . . . . . . . . . . . . . . . . . 234
Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . 357
Pad Life System . . . . . . . . . . . . . . 356
Braking . . . . . . . . . . . . . . . . . . . . . . . . . 188 AutomaticEmergency (AEB) . . . . . . . . . . . 270
Braking System Front Pedestrian (FPB) . . . . . . . 272
Break-In, New Vehicle . . . . . . . . . . 208
Bulb Replacement Center High-Mounted
Stoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . 369
Halogen Bulbs . . . . . . . . . . . . . . . . 367
Headlamp Aiming . . . . . . . . . . . . . 366
Headlamps . . . . . . . . . . . . . . . . . . . 367 Bulb Replacement (cont'd)
Headlamps, Front Turn
Signal, Sidemarker, and
Parking Lamps . . . . . . . . . . . . . . 367
License Plate Lamps . . . . . . . . . 369
Taillamps, Turn Signal, Stoplamps, and Back-up
Lamps . . . . . . . . . . . . . . . . . . . . . . 368
Buying New Tires . . . . . . . . . . . . . . . 399
C
Calibration . . . . . . . . . . . . . . . . . . . . . . 121
California Perchlorate Materials
Requirements . . . . . . . . . . . . . . . 329
California Proposition
65 Warning . . . . . . . . . .329, 358, 419, Back Cover
Canadian Vehicle Owners . . . . . . . . 2
Capacities and Specifications . . . . . . . . . . . . . . . . . 459
Carbon Monoxide Engine Exhaust . . . . . . . . . . . . . . . 220
Tailgate . . . . . . . . . . . . . . . . . . . . . . . . . 28
Winter Driving . . . . . . . . . . . . . . . . 197
Cargo Tie-Downs . . . . . . . . . . . . . . . . . . . . .116

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/-
Mexico-13337776) - 2020 - CRC - 4/4/19
490 Index
Caution, Danger, and Warning . . . . 3
Center Console Storage . . . . . . . . 114
Center High-MountedStoplamp (CHMSL) and
Cargo Lamp . . . . . . . . . . . . . . . . . . . 369
Center Seat . . . . . . . . . . . . . . . . . . . . . 56
Chains, Tire . . . . . . . . . . . . . . . . . . . . 404
Charging Wireless . . . . . . . . . . . . . . . . . . . . . . 124
Charging System Light . . . . . . . . . 138
Check Engine Light (MalfunctionIndicator) . . . . . . . . . . . . . . . . . . . . 138
Ignition Transmission Lock . . . 363
Child Restraints Infants and Young Children . . . . . 87
Lower Anchors and Tethers
for Children . . . . . . . . . . . . . . . . . . . 92
Older Children . . . . . . . . . . . . . . . . . . 85
Securing . . . . . . . . . . . . 105, 108, 109
Systems . . . . . . . . . . . . . . . . . . . . . . . . 89
Circuit Breakers . . . . . . . . . . . . . . . . 370
Cleaning Exterior Care . . . . . . . . . . . . . . . . . 429
Interior Care . . . . . . . . . . . . . . . . . . 435
Climate Control Systems . . . . . . . 177 Air Conditioning . . . . . . . . . . . . . . 177
Dual Automatic . . . . . . . . . . . . . . . 179 Climate Control Systems (cont'd)
Heating . . . . . . . . . . . . . . . . . . . . . . . 177
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Cluster, Instrument . . . . . . . . . . . . . 127
Collision Damage Repair . . . . . . . 470
Compartments Storage . . . . . . . . . . . . . . . . . . . . . . . .113
Compass . . . . . . . . . . . . . . . . . . . . . . . 121
Connected Services Connections . . . . . . . . . . . . . . . . . . 486
Diagnostics . . . . . . . . . . . . . . . . . . . 487
Navigation . . . . . . . . . . . . . . . . . . . . 485
Connections Connected Services . . . . . . . . . . 486
Control Hill Descent . . . . . . . . . . . . . . . . . . 237
Traction and ElectronicStability . . . . . . . . . . . . . . . . . . . . . 235
Control Light Hill Descent . . . . . . . . . . . . . . . . . . 142
Control of a Vehicle . . . . . . . . . . . . . 188
Convex Mirrors . . . . . . . . . . . . . . . . . . 40
Coolant Engine Temperature Gauge . . 134
Engine TemperatureWarning Light . . . . . . . . . . . . . . . 145
Cooling . . . . . . . . . . . . . . . . . . . . 177, 179
Cooling System . . . . . . . . . . . . . . . . . 346 Courtesy Transportation
Program . . . . . . . . . . . . . . . . . . . . . . . 469
Cruise Control . . . . . . . . . . . . . . . . . . 243 Light . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Cruise Control, Adaptive . . . . . . . . 245
Cupholders . . . . . . . . . . . . . . . . . . . . . 113
Customer Assistance . . . . . . . . . . . 466 Offices . . . . . . . . . . . . . . . . . . . . . . . . 465
Text Telephone (TTY)Users . . . . . . . . . . . . . . . . . . . . . . . 466
Customer Information
Publications OrderingInformation . . . . . . . . . . . . . . . . . . 472
Customer Satisfaction Procedure . . . . . . . . . . . . . . . . . . . . . 463
Cybersecurity . . . . . . . . . . . . . . . . . . . 475
D
Damage Repair, Collision . . . . . . . 470
Danger, Warning, and Caution . . . . 3
Data Collection
Infotainment System . . . . . . . . . . 476
OnStar . . . . . . . . . . . . . . . . . . . . . . . 476
Data Recorders, Event . . . . . . . . . 475
Daytime Running Lamps (DRL) . . . . . . . . . . . . . . . . . . 168
Defensive Driving . . . . . . . . . . . . . . . 187
Delayed Locking . . . . . . . . . . . . . . . . . 26

GMC Sierra/Sierra Denali Owner Manual (GMNA-Localizing-U.S./Canada/-
Mexico-13337776) - 2020 - CRC - 4/4/19
Index 491
DiagnosticsConnected Services . . . . . . . . . . 487
Differential, Limited-Slip . . . . . . . . 242
Distracted Driving . . . . . . . . . . . . . . . 187
Dome Lamps . . . . . . . . . . . . . . . . . . . 172
Door Ajar Light . . . . . . . . . . . . . . . . . . . . . 148
Delayed Locking . . . . . . . . . . . . . . . . 26
Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Power Locks . . . . . . . . . . . . . . . . . . . . 26
Drive Belt Routing, Engine . . . . . . 462
Driver Assistance Systems . . . . . 256
Driver Information
Center (DIC) . . . . . . . . . . . . . 148, 149
Driver Mode Control . . . . . . . . . . . . 238
Driver Mode Control Light . . . . . . 145
Driving Assistance Systems . . . . . . . . . . 268
Better Fuel Economy . . . . . . . . . 186
Characteristics andTowing Tips . . . . . . . . . . . . . . . . . 287
Defensive . . . . . . . . . . . . . . . . . . . . . 187
Drunk . . . . . . . . . . . . . . . . . . . . . . . . . 188
Hill and Mountain Roads . . . . . . 197
If the Vehicle is Stuck . . . . . . . . . 199
Loss of Control . . . . . . . . . . . . . . . 190
Off-Road . . . . . . . . . . . . . . . . . . . . . 191
Off-Road Recovery . . . . . . . . . . . 190 Driving (cont'd)
Vehicle Load Limits . . . . . . . . . . . 200
Wet Roads . . . . . . . . . . . . . . . . . . . 196
Winter . . . . . . . . . . . . . . . . . . . . . . . . 197
Dual Automatic Climate Control System . . . . . . . . . . . . . . . . 179
E
E85 or FlexFuel . . . . . . . . . . . . . . . . 282
Electric Brake Boost . . . . . . . . . . . . 232
Electric Parking Brake . . . . . . . . . . 233
Electric Parking Brake Light . . . . 141
Electrical Equipment,Add-On . . . . . . . . . . . . . . . . . . . . . . . 322
Electrical System Engine Compartment FuseBlock . . . . . . . . . . . . . . . . . . . . . . . . 371
Fuses and Circuit Breakers . . . 370
Instrument Panel Fuse Block . . . . . . . . . . . . . . . . . . . 374, 376
Overload . . . . . . . . . . . . . . . . . . . . . 370
Electronic Stability Control (ESC) Off Light . . . . . . . . . . . . . . . . 144
Emergency
OnStar . . . . . . . . . . . . . . . . . . . . . . . 478
Engine Air Cleaner/Filter . . . . . . . . . . . . . 344 Engine (cont'd)
Check Light (Malfunction
Indicator) . . . . . . . . . . . . . . . . . . . . 138
Compartment Overview . . . . . . . 332
Coolant Temperature
Gauge . . . . . . . . . . . . . . . . . . . . . . 134
Coolant Temperature Warning Light . . . . . . . . . . . . . . . 145
Cooling System . . . . . . . . . . . . . . . 346
Drive Belt Routing . . . . . . . . . . . . 462
Exhaust . . . . . . . . . . . . . . . . . . . . . . 220
Fan . . . . . . . . . . . . . . . . . . . . . . . . . . . 353
Heater . . . . . . . . . . . . . . . . . . . . . . . . 215
Oil Life System . . . . . . . . . . . . . . . 341
Oil Pressure Gauge . . . . . . . . . . 133
Oil Pressure Light . . . . . . . . . . . . 146
Overheated Protection Operating Mode . . . . . . . . . . . . . 352
Overheating . . . . . . . . . . . . . . . . . . 351
Power Messages . . . . . . . . . . . . . 156
Running While Parked . . . . . . . . 220
Starting . . . . . . . . . . . . . . . . . . . . . . . 212
Engine Air Filter Life System . . . . 343
Entry Lighting . . . . . . . . . . . . . . . . . . . 173
Equipment, Towing . . . . . . . . . . . . . 296
Event Data Recorders . . . . . . . . . . 475
Exit Lighting . . . . . . . . . . . . . . . . . . . . 173
Extended Parking . . . . . . . . . . . . . . . 219