2008 GMC SIERRA check engine light

If the Light is Flashing
The following can prevent more serious damage to your
vehicle:
Reduce vehicle speed.
Avoid hard accelerations.
Avoid steep uphill grades.
If you are towing a trailer, reduce the amount of
cargo being hauled as soon as it is possible.
If the light stops ashing and remains on steady, see “If
the Light Is On Steady” following.
If the light continues to ash, when it is safe to do so,
stop the vehicle. Find a safe place to park the vehicle.
Turn the ignition off, wait at least 10 seconds, and restart
the engine. If the light remains on steady, see “If the
Light Is On Steady” following. If the light is still ashing,
follow the previous steps and see your dealer/retailer
for service as soon as possible.
If the Light Is On Steady
You might be able to correct the emission system
malfunction by considering the following:
Did you recently put fuel into your vehicle?
If so, reinstall the fuel cap, making sure to fully install
the cap. SeeFilling the Tank on page 5-10. The
diagnostic system can determine if the fuel cap hasbeen left off or improperly installed. A loose or missing
fuel cap allows fuel to evaporate into the atmosphere.
A few driving trips with the cap properly installed should
turn the light off.
Did you just drive through a deep puddle of water?
If so, your vehicle’s electrical system might be wet. The
condition is usually corrected when the electrical system
dries out. A few driving trips should turn the light off.
Have you recently changed brands of fuel?
If so, be sure to fuel your vehicle with quality fuel. See
Gasoline Octane on page 5-6. Poor fuel quality causes
the engine not to run as efficiently as designed. You
might notice this as stalling after start-up, stalling when
you put the vehicle into gear, misring, hesitation on
acceleration, or stumbling on acceleration — these
conditions might go away once the engine is warmed up.
This will be detected by the system and cause the light to
turn on.
If you experience one or more of these conditions,
change the fuel brand you use. It will require at least
one full tank of the proper fuel to turn the light off.
If none of the above steps have made the light turn off,
your dealer/retailer can check the vehicle. Your
dealer/retailer has the proper test equipment and
diagnostic tools to x any mechanical or electrical
problems that might have developed.
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Emissions Inspection and Maintenance
Programs
Some state/provincial and local governments have or
might begin programs to inspect the emission control
equipment on your vehicle. Failure to pass this
inspection could prevent you from getting a vehicle
registration.
Here are some things you need to know to help your
vehicle pass an inspection:
Your vehicle will not pass this inspection if the check
engine light is on or not working properly.
Your vehicle will not pass this inspection if the OBD
(on-board diagnostic) system determines that critical
emission control systems have not been completely
diagnosed by the system. The vehicle would be
considered not ready for inspection. This can happen if
you have recently replaced the battery or if the
battery has run down. The diagnostic system is
designed to evaluate critical emission control systems
during normal driving. This can take several days
of routine driving. If you have done this and your vehicle
still does not pass the inspection for lack of OBD
system readiness, your dealer/retailer can prepare the
vehicle for inspection.
Oil Pressure Gage
Your vehicle may have an engine oil pressure gage. It
shows the engine oil pressure in psi (pounds per square
inch) when the engine is running. Canadian vehicles
indicate pressure in kPa (kilopascals).
Oil pressure may vary with engine speed, outside
temperature and oil viscosity, but if readings are outside
the normal operating range, the oil pressure light will
come on. SeeOil Pressure Light on page 3-51for more
information.United States
Canada
3-50

A reading outside the normal operating range may be
caused by a dangerously low oil level or some other
problem causing low oil pressure. Check your oil
as soon as possible. See “OIL PRESSURE LOW” under
DIC Warnings and Messages on page 3-63and
Engine Oil (Gasoline Engine) on page 5-15.
{CAUTION:
Do not keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches re. You or others could be burned.
Check your oil as soon as possible and have
your vehicle serviced.
Notice:Lack of proper engine oil maintenance may
damage the engine. The repairs would not be
covered by your warranty. Always follow the
maintenance schedule in this manual for changing
engine oil.
Oil Pressure Light
{CAUTION:
Do not keep driving if the oil pressure is low. If
you do, your engine can become so hot that it
catches re. You or others could be burned.
Check your oil as soon as possible and have
your vehicle serviced.
Notice:Lack of proper engine oil maintenance may
damage the engine. The repairs would not be covered
by your warranty. Always follow the maintenance
schedule in this manual for changing engine oil.
This light will come on
briey when you start your
engine. If it does not,
have your vehicle serviced.
When the light comes on and stays on, it means that oil
is not owing through your engine properly. You
could be low on oil and you might have some other
system problem.
3-51

The following are the possible messages that can be
displayed and some information about them.
If your vehicle has the DURAMAX
®Diesel engine, see
the DURAMAX®Diesel manual for more information.
CHANGE ENGINE OIL SOON
This message displays when the engine oil needs to be
changed. When you change the engine oil, be sure
to reset the CHANGE ENGINE OIL SOON message.
SeeEngine Oil Life System on page 5-18for information
on how to reset the message. SeeEngine Oil (Gasoline
Engine) on page 5-15andScheduled Maintenance
(Gasoline Engine) on page 6-4for more information.
CHECK TIRE PRESSURE
If your vehicle has the Tire Pressure Monitor System
(TPMS), this message displays when the pressure
in one or more of the vehicle’s tires needs to be
checked. This message also displays LEFT FRONT,
RIGHT FRONT, LEFT REAR, or RIGHT REAR to
indicate which tire needs to be checked. You can
receive more than one tire pressure message at a time.
To read the other messages that may have been
sent at the same time, press the set/reset button or the
trip odometer reset stem. If a tire pressure message
appears on the DIC, stop as soon as you can. Have the
tire pressures checked and set to those shown on the
Tire Loading Information label. SeeTires on page 5-66,Loading Your Vehicle on page 4-36, andInflation - Tire
Pressure on page 5-74. The DIC also shows the tire
pressure values. See “DIC Operation and Displays (With
DIC Buttons)” earlier in this section. If the tire pressure
is low, the low tire pressure warning light comes on.
SeeTire Pressure Light on page 3-47.
CHECK TRAILER WIRING
On vehicles with the Integrated Trailer Brake Control
(ITBC) system, this message may display and a chime
may sound when one of the following conditions exists:
A trailer with electric brakes becomes disconnected
from the vehicle.
If the disconnect occurs while the vehicle is
stopped, this message clears itself after a
short time.
If the disconnect occurs while the vehicle is
moving, this message stays on until the ignition
is turned off.
There is a short in the wiring to the electric trailer
brakes.
When this message displays, power is no longer
available to the trailer brakes.
As soon as it is safe to do so, carefully pull your vehicle
over to the side of the road and turn the ignition off.
Check the wiring connection to the trailer and turn the
ignition back on. This message clears if the trailer
3-64

SERVICE AIR BAG
This message displays if there is a problem with the
airbag system. Have your dealer/retailer inspect
the system for problems. SeeAirbag Readiness Light
on page 3-38andAirbag System on page 1-68for more
information.
SERVICE BATTERY CHARGING
SYSTEM
On some vehicles, this message displays if there is a
problem with the battery charging system. Under certain
conditions, the charging system light may also turn
on in the instrument panel cluster. SeeCharging System
Light on page 3-43. Driving with this problem could
drain the battery. Turn off all unnecessary accessories.
Have the electrical system checked as soon as
possible. See your dealer/retailer.
SERVICE BRAKE SYSTEM
This message displays along with the brake system
warning light if there is a problem with the brake system.
SeeBrake System Warning Light on page 3-44. If this
message appears, stop as soon as possible and turn off
the vehicle. Restart the vehicle and check for the
message on the DIC display. If the message is still
displayed or appears again when you begin driving, the
brake system needs service as soon as possible.
See your dealer/retailer.
SERVICE BRAKES SOON
This message displays if there is a problem with the
brake system. If this message appears, stop as soon as
possible and turn off the vehicle. Restart the vehicle
and check for the message on the DIC display. If
the message is still displayed or appears again when
you begin driving, the brake system needs service. See
your dealer/retailer.
SERVICE PARK ASSIST
If your vehicle has the Ultrasonic Rear Parking Assist
(URPA) system, this message displays if there is a
problem with the URPA system. Do not use this system
to help you park. SeeUltrasonic Rear Parking Assist
(URPA) on page 2-63for more information. See
your dealer/retailer for service.
SERVICE STABILITRAK
If your vehicle has StabiliTrak®and this message
displays, it means there may be a problem with the
StabiliTrak
®system. If you see this message, try to reset
the system. Stop; turn off the engine for at least
15 seconds; then start the engine again. If this message
still comes on, it means there is a problem. You
should see your dealer/retailer for service. The vehicle
is safe to drive, however, you do not have the benet
of StabiliTrak
®, so reduce your speed and drive
accordingly.
3-68

SERVICE THEFT DETERRENT SYSTEM
This message displays when there is a problem with
the theft-deterrent system. The vehicle may or may not
restart so you may want to take the vehicle to your
dealer/retailer before turning off the engine. See
PASS-Key
®III+ Operation on page 2-20for more
information.
SERVICE TIRE MONITOR SYSTEM
If your vehicle has the Tire Pressure Monitor System
(TPMS), this message displays if a part on the system is
not working properly. The tire pressure light also
ashes and then remains on during the same ignition
cycle. SeeTire Pressure Light on page 3-47. Several
conditions may cause this message to appear. SeeTire
Pressure Monitor Operation on page 5-78for more
information. If the warning comes on and stays on, there
may be a problem with the TPMS. See your
dealer/retailer.
SERVICE TRACTION CONTROL
If your vehicle has StabiliTrak®, this message displays
when there is a problem with the Traction Control
System (TCS). When this message displays, the system
will not limit wheel spin. Adjust your driving accordingly.
See your dealer/retailer for service. SeeStabiliTrak
®
System on page 4-6for more information.
SERVICE TRAILER BRAKE SYSTEM
On vehicles with the Integrated Trailer Brake Control
(ITBC) system, this message displays and a chime
sounds when there is a problem with the ITBC system.
When this message displays, power is no longer
available to the trailer brakes.
As soon as it is safe to do so, carefully pull your vehicle
over to the side of the road and turn the ignition off.
Check the wiring connection to the trailer and turn the
ignition back on. If this message still displays, either your
vehicle or the trailer needs service. See your
dealer/retailer.
See “Integrated Trailer Brake Control System” under
Towing a Trailer on page 4-55for more information.
3-69

STABILITRAK OFF
If your vehicle has StabiliTrak®, this message displays
when you turn off StabiliTrak®, or when the stability
control has been automatically disabled. To limit wheel
spin and realize the full benets of the stability
enhancement system, you should normally leave
StabiliTrak
®on. However, you should turn StabiliTrak®
off if your vehicle gets stuck in sand, mud, ice, or
snow and you want to rock your vehicle to attempt to
free it, or if you are driving in extreme off-road conditions
and require more wheel spin. SeeIf Your Vehicle is
Stuck in Sand, Mud, Ice, or Snow on page 4-34. To turn
the StabiliTrak
®system on or off, seeStabiliTrak®
System on page 4-6.
There are several conditions that can cause this
message to appear.
One condition is overheating, which could occur if
StabiliTrak®activates continuously for an extended
period of time.
The message also displays if the brake system
warning light is on. SeeBrake System Warning
Light on page 3-44.
The message could display if the stability system
takes longer than usual to complete its diagnostic
checks due to driving conditions.
The message displays if an engine or vehicle
related problem has been detected and the vehicle
needs service. See your dealer/retailer.
The message also displays if the vehicle is shifted
into 4LO.
The message turns off as soon as the conditions that
caused the message to be displayed are no longer
present.
TIGHTEN GAS CAP
This message may display along with the check engine
light on the instrument panel cluster if the vehicle’s
fuel cap is not tightened properly. SeeMalfunction
Indicator Lamp on page 3-48. Reinstall the fuel cap fully.
SeeFilling the Tank on page 5-10. The diagnostic
system can determine if the fuel cap has been left off or
improperly installed. A loose or missing fuel cap
allows fuel to evaporate into the atmosphere. A few
driving trips with the cap properly installed should turn
this light and message off.
3-70

Avoid needless heavy braking. Some people drive
in spurts — heavy acceleration followed by heavy
braking — rather than keeping pace with traffic. This is
a mistake. The brakes might not have time to cool
between hard stops. The brakes will wear out much
faster if you do a lot of heavy braking. If you keep pace
with the traffic and allow realistic following distances,
you will eliminate a lot of unnecessary braking.
That means better braking and longer brake life.
If your vehicle’s engine ever stops while you are driving,
brake normally but do not pump the brakes. If you do,
the pedal could get harder to push down. If the
engine stops, you will still have some power brake
assist. But you will use it when you brake. Once the
power assist is used up, it can take longer to stop and
the brake pedal will be harder to push.
Adding non-dealer/non-retailer accessories can affect
your vehicle’s performance. SeeAccessories and
Modifications on page 5-4.Antilock Brake System (ABS)
Your vehicle has the Antilock Brake System (ABS), an
advanced electronic braking system that will help
prevent a braking skid.
When you start the engine and begin to drive away, ABS
will check itself. You might hear a momentary motor or
clicking noise while this test is going on. This is normal.
If there is a problem with
ABS, this warning light will
stay on. SeeAntilock
Brake System Warning
Light on page 3-45.
Along with ABS, your vehicle has a Dynamic Rear
Proportioning (DRP) system. If there is a DRP problem,
both the brake and ABS warning lights come on
accompanied by a 10-second chime. The lights and
chime will come on each time the ignition is turned on
until the problem is repaired. See your dealer/retailer for
service.
4-4