GMC Terrain 2018 Owner's Manual page 127

126 Instruments and Controls
Caution (Continued)
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 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
0 255.
Light Flashing (Gasoline
Engine Only)
If the light is flashing : A
malfunction has been detected that
could damage the emission control
system and increase vehicle
emissions. Diagnosis and service
may be required.
To help prevent damage, reduce
vehicle speed and avoid hard
accelerations and uphill grades.
If towing a trailer, reduce the
amount of cargo being hauled as
soon as possible.
If the light continues to flash, find a
safe place to park. Turn the vehicle
off and wait at least 10 seconds
before restarting the engine. If the
light is still flashing, follow the
previous guidelines and see your
dealer for service as soon as
possible.
Light on Steady (All Engines)
If the light is on steady : A
malfunction has been detected.
Diagnosis and service may be
required.
Check the following:
If fuel has been added to the
vehicle using the capless funnel
adapter, make sure that it has
been removed. See Filling the
Tank with a Portable Gas Can
under Filling the Tank (Gasoline)
0 241 or Filling the Tank (Diesel)
0 243. The diagnostic system
can detect if the adapter has
been left installed in the vehicle,
allowing fuel to evaporate into
the atmosphere. A few driving
trips with the adapter removed
may turn off the light.
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 (Gasoline) 0 231 or
Fuel for Diesel Engines 0 233.
If the light remains on, see your
dealer.