Chevrolet 4500HD Series 2019 Manual page 193

192 Driving and Operating
Warning (Continued)
Do not dilute DEF with water.
Do not add substances such as
gasoline or diesel fuel to the DEF
tank. You and others could be
seriously injured.
Caution
When opening the DEF tank cap,
be careful not to let dirt or other
foreign matter enter inside the
DEF tank. Intrusion of foreign
matter can cause a clogging of
the filter or affect the quality of
DEF, which may result in a SCR
system failure.
If DEF is spilled on the body or
frame, it may cause generation of
rust, so wipe it off and then rinse
it away with water.
When DEF dries it will leave a
crystalline residue, this condition is
normal. Wash with water or wipe
away the residue to prevent it from
entering the DEF tank.
Adding DEF in Cold Weather
DEF freezes at low temperature but
the engine coolant circulates to
thaw the DEF tank and to prevent
DEF from freezing. Vehicle can be
driven normally when DEF is frozen.
If the refill diesel exhaust fluid (DEF)
warning light is on and the
remaining DEF in the DEF tank is
frozen, the warning lights, indicator
lights and restriction will not be
canceled until the DEF thaws even
if the DEF tank is refilled.
It is not recommended parking the
vehicle for long periods with the refill
diesel exhaust fluid (DEF) warning
light on in cold weather. The DEF
gauge will not register correctly
should the DEF freeze in this
condition causing the DEF low level
warning system not to reset when
DEF is added. Take the following
actions to avoid this condition in
cold weather:
1. Refill the DEF as soon as
possible after parking the
vehicle.
2. Turn the engine control switch
to the ON position from the
LOCK position.
3. Wait for the warning buzzers
and warning lights to turn off.
4. If the buzzer does not stop,
return the engine control switch
back to the LOCK position and
add more DEF, and then start
over from step (2) above.
5. Turn the engine control switch
to the LOCK position.
The DEF freezes at approximately
11 °C (12 °F).
In cold weather, when the vehicle is
left without performing these actions
and the DEF tank freezes, the low
DEF level warnings and indicators
may not turn off when DEF is added
until after the tank defrosts.