Malfunction Indicator Lamp; Light) - Chevrolet GMC Duramax 2023 Manual

6 Instruments and Controls
Uplevel GMC English Cluster Shown, Metric Similar

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 with the engine not
running. See Ignition Positions in the
owner s manual.
This light may also come on when the
system has detected a problem with the
Diesel Exhaust Fluid (DEF) management
system. See Diesel Exhaust Fluid 0 19.
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
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