Malfunction Indicator Lamp; Engine Light) - Chevrolet Silverado 1500 2021 Owner's Manual

116 Instruments and Controls

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 and the engine is not
running. See Ignition Positions (Keyless
Access) 0 230 or
Ignition Positions (Key Access) 0 229.
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
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 0 322.
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.
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 (Pickup Model)
0 285 or
Filling the Tank (Chassis Cab
Model) 0 286. 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.