2012 GMC YUKON check engine light

Black plate (7,1)GMC Yukon/Yukon XL Owner Manual - 2012
Keys, Doors, and Windows 2-7
The vehicle cannot be remote
started if the key is in the ignition,
the hood is not closed, or if there is
an emission control system
malfunction and the check engine
light is on.
Also, the engine will turn off during a
remote vehicle start if the coolant
temperature gets too high or if the
oil pressure gets low.
Remote Start Ready
If the vehicle does not have the
remote vehicle start feature, it may
have the remote start ready feature.
This feature allows your dealer to
add the manufacturer's remote
vehicle start feature.
See your dealer to add the
manufacturer's remote vehicle start
feature to the vehicle.
Door Locks
{WARNING
Unlocked doors can be
dangerous.
.Passengers, especially
children, can easily open the
doors and fall out of a moving
vehicle. When a door is
locked, the handle will not
open it. The chance of being
thrown out of the vehicle in a
crash is increased if the
doors are not locked. So, all
passengers should wear
safety belts properly and the
doors should be locked
whenever the vehicle is
driven.(Continued)
WARNING (Continued)
.Young children who get into
unlocked vehicles may be
unable to get out. A child can
be overcome by extreme heat
and can suffer permanent
injuries or even death from
heat stroke. Always lock the
vehicle whenever leaving it.
.Outsiders can easily enter
through an unlocked door
when you slow down or stop
the vehicle. Locking the doors
can help prevent this from
happening.
There are several ways to lock and
unlock the vehicle.
From outside, use the Remote
Keyless Entry (RKE) transmitter or
the key in the driver door.

Black plate (16,1)GMC Yukon/Yukon XL Owner Manual - 2012
2-16 Keys, Doors, and Windows
vehicle will be discouraged because
of the high number of electrical key
codes.
If the engine does not start and the
security light on the instrument
panel cluster comes on when trying
to start the vehicle, there may be a
problem with the theft-deterrent
system. Turn the ignition off and try
again.
If the engine still does not start, and
the key appears to be undamaged,
try another ignition key. At this time,
you may also want to check the
fuse. SeeFuses and Circuit
Breakers on page 10‑40. If the
engine still does not start with the
other key, the vehicle needs service.
If the vehicle does start, the first key
may be faulty. See your dealer who
can service the PASS-Key III+ to
have a new key made.
It is possible for the PASS-Key III+
decoder to learn the transponder
value of a new or replacement key.
Up to 10 keys may be programmed
for the vehicle. The following procedure is for programming
additional keys only. If all the
currently programmed keys are lost
or do not operate, you must see
your dealer or a locksmith who can
service PASS-Key III+ to have keys
made and programmed to the
system.
See your dealer or a locksmith who
can service PASS-Key III+ to get a
new key blank cut exactly as the
ignition key that operates the
system.
To program the new additional key:
1. Verify that the new key has a
1
stamped on it.
2. Insert the original, already programmed key in the ignition
and start the engine. If the
engine will not start, see your
dealer for service.
3. After the engine has started, turn the key to LOCK/OFF, and
remove the key. 4. Insert the new key to be
programmed and turn it to the
ON/RUN position within
five seconds of turning the
ignition to the LOCK/OFF
position in Step 3.
The security light will turn off
once the key has been
programmed.
5. Repeat Steps 1 through 4 if additional keys are to be
programmed.
If you lose or damage your
PASS-Key III+ key, see your dealer
or a locksmith who can service
PASS-Key III+ to have a new
key made.
Do not leave the key or device that
disarms or deactivates the
theft-deterrent system in the vehicle.

Black plate (11,1)GMC Yukon/Yukon XL Owner Manual - 2012
Instruments and Controls 5-11
Warning Lights,
Gauges, and
Indicators
Warning lights and gauges can
signal that something is wrong
before it becomes serious enough
to cause an expensive repair or
replacement. Paying attention to the
warning lights and gauges could
prevent injury.Warning lights come on when there
could be a problem with a vehicle
function. Some warning lights come
on briefly when the engine is started
to indicate they are working.
Gauges can indicate when there
could be a problem with a vehicle
function. Often gauges and warning
lights work together to indicate a
problem with the vehicle.
When one of the warning lights
comes on and stays on while
driving, or when one of the gauges
shows there may be a problem,
check the section that explains what
to do. Follow this manual's advice.
Waiting to do repairs can be costly
and even dangerous.

Black plate (18,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-18 Instruments and Controls
This cycle may continue several
times if the driver remains or
becomes unbuckled while the
vehicle is moving.
If the driver safety belt is buckled,
neither the light nor the chime
comes on.
Passenger Safety Belt
Reminder Light
When the vehicle is started, this
light flashes and a chime may come
on to remind front passengers to
fasten their safety belt. Then the
light stays on solid until the belt is
buckled.For more information see
Passenger Airbag Status Indicator
on page 5‑19.
This cycle continues several times if
the front passenger remains or
becomes unbuckled while the
vehicle is moving.
If the front passenger safety belt is
buckled, neither the chime nor the
light comes on.
The front passenger safety belt
reminder light and chime may turn
on if an object is put on the seat
such as a briefcase, handbag,
grocery bag, laptop, or other
electronic device. To turn off the
reminder light and/or chime, remove
the object from the seat or buckle
the safety belt.
Airbag Readiness Light
The system checks the airbag's
electrical system for possible
malfunctions. If the light stays on it
indicates there is an electrical
problem. The system check includes
the airbag sensor(s), passenger
sensing system, the pretensioners,
the airbag modules, the wiring, and
the crash sensing and diagnostic
module. For more information on the
airbag system, see
Airbag System
on page 3‑30.
The airbag readiness light comes on
solid for a few seconds when the
engine is started. If the light does
not come on then, have it fixed
immediately.

Black plate (20,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-20 Instruments and Controls
Then, after several more seconds,
the status indicator will light either
ON or OFF, or either the on or off
symbol to let you know the status of
the right front passenger frontal
airbag.
If the word ON or the on symbol is
lit on the passenger airbag status
indicator, it means that the right
front passenger frontal airbag is
enabled (may inflate).
If the word OFF or the off symbol is
lit on the airbag status indicator, it
means that the passenger sensing
system has turned off the right front
passenger frontal airbag.
If, after several seconds, both status
indicator lights remain on, or if there
are no lights at all, there may be a
problem with the lights or the
passenger sensing system. See
your dealer for service.{WARNING
If the airbag readiness light ever
comes on and stays on, it means
that something may be wrong
with the airbag system. To help
avoid injury to yourself or others,
have the vehicle serviced right
away. SeeAirbag Readiness
Light on page 5‑18 for more
information, including important
safety information.
Charging System Light
This light comes on briefly when the
ignition key is turned to START, but
the engine is not running, as a
check to show it is working. If it does not, have the vehicle
serviced by your dealer.
The light should go out once the
engine starts. If it stays on,
or comes on while driving, there
could be a problem with the
charging system. A charging system
message in the Driver Information
Center (DIC) can also appear. See
Battery Voltage and Charging
Messages on page 5‑38
for more
information. This light could indicate
that there are problems with a
generator drive belt, or that there is
an electrical problem. Have it
checked right away. If the vehicle
must be driven a short distance with
the light on, turn off accessories,
such as the radio and air
conditioner.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.

Black plate (21,1)GMC Yukon/Yukon XL Owner Manual - 2012
Instruments and Controls 5-21
Malfunction
Indicator Lamp
A computer system called OBD II
(On-Board Diagnostics-Second
Generation) monitors the operation
of the vehicle to ensure emissions
are at acceptable levels, to produce
a cleaner environment. This light
comes on when the vehicle is
placed in ON/RUN, as a check to
show it is working. If it does not,
have the vehicle serviced by your
dealer. SeeIgnition Positions on
page 9‑22 for more information.
If the malfunction indicator lamp
comes on and stays on while the
engine is running, this indicates that
there is an OBD II problem and
service is required.
Malfunctions often are indicated by
the system before any problem is
apparent. Being aware of the light
can prevent more serious damage
to the vehicle. This system assists
the service technician in correctly
diagnosing any malfunction.
Notice:If the vehicle is
continually driven with this light
on, the emission controls might
not work as well, the vehicle fuel
economy might not be as good,
and the engine might not run as
smoothly. This could lead to
costly repairs that might not be
covered by the vehicle warranty. Notice:
Modifications made to the
engine, transmission, exhaust,
intake, or fuel system of the
vehicle or the replacement of the
original tires with other than
those of the same Tire
Performance Criteria (TPC) can
affect the vehicle's emission
controls and can cause this light
to come on. Modifications to
these systems could lead to
costly repairs not covered by the
vehicle warranty. This could also
result in a failure to pass a
required Emission Inspection/
Maintenance test. See
Accessories and Modifications on
page 10‑3.
This light comes on during a
malfunction in one of two ways:
Light Flashing: A misfire condition
has been detected. A misfire
increases vehicle emissions and
could damage the emission control
system on the vehicle. Diagnosis
and service might be required.

Black plate (22,1)GMC Yukon/Yukon XL Owner Manual - 2012
5-22 Instruments and Controls
To prevent more serious damage to
the vehicle:
.Reduce vehicle speed.
.Avoid hard accelerations.
.Avoid steep uphill grades.
.If towing a trailer, reduce the
amount of cargo being hauled as
soon as it is possible.
If the light continues to flash, stop
and park the vehicle. Turn the
vehicle off, wait at least 10 seconds,
and restart the engine. If the light is
still flashing, follow the previous
steps and see your dealer for
service as soon as possible.
Light On Steady: An emission
control system malfunction has
been detected on the vehicle.
Diagnosis and service might be
required. The following may correct an
emission system malfunction:
.Check that the fuel cap is fully
installed. See
Filling the Tank on
page 9‑65. 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 the
light off.
.Check that good quality fuel is
used. Poor fuel quality causes
the engine not to run as
efficiently as designed and may
cause stalling after start-up,
stalling when the vehicle is
changed into gear, misfiring,
hesitation on acceleration,
or stumbling on acceleration.
These conditions might go away
once the engine is warmed up. If one or more of these conditions
occurs, change the fuel brand used.
It will require at least one full tank of
the proper fuel to turn the light off.
See
Recommended Fuel on
page 9‑62.
If none of the above have made the
light turn off, your dealer can check
the vehicle. The dealer has the
proper test equipment and
diagnostic tools to fix any
mechanical or electrical problems
that might have developed.

Black plate (27,1)GMC Yukon/Yukon XL Owner Manual - 2012
Instruments and Controls 5-27
Engine Oil Pressure Light
{WARNING
Do not keep driving if the oil
pressure is low. The engine can
become so hot that it catches fire.
Someone could be burned. Check
the oil as soon as possible and
have the vehicle serviced.
Notice: Lack of proper engine oil
maintenance can damage the
engine. The repairs would not be
covered by the vehicle warranty.
Always follow the maintenance
schedule for changing engine oil.
This light comes on briefly while
starting the engine. If it does not,
have the vehicle serviced by your dealer. If the system is working
normally the indicator light then
goes off.
If the light comes on and stays on, it
means that oil is not flowing through
the engine properly. The vehicle
could be low on oil and it might
have some other system problem.
If the vehicle is a hybrid, see the
hybrid supplement for more
information.
Low Fuel Warning Light
This light, under the fuel gauge,
comes on briefly while the engine is
being started.
This light and a chime come on
when the fuel tank is low on fuel.
The Driver Information Center also
displays a FUEL LEVEL LOW
message. See
Fuel System
Messages on page 5‑41 for more
information. When fuel is added this
light and message should go off.
If they do not, have the vehicle
serviced by your dealer.
Security Light
The security light should come on
briefly as the engine is started. If the
system is working normally, the
indicator light turns off. If it does not
come on, have the vehicle serviced
by your dealer.
If the light stays on and the engine
does not start, there could be a
problem with the theft-deterrent
system.