HEST (High Exhaust System Temperature)

HEST (High Exhaust System Temperature)
The Caterpillar CRS system is designed to operate in automatic
mode and perform regeneration as required without any driver
action. Manual regeneration is a backup to the automatic mode.
Automatic Regeneration
To complete an automatic regeneration, the dash switch (if
equipped) must be in the automatic regeneration position. The
Inhibit or Disable Switch (if equipped) must NOT be enabled or
“on.” Caterpillar recommends automatic regeneration for most
If the DPF soot loading reaches level 3, the DPF Lamp starts
to flash and the Check Engine Lamp comes on. At this point,
Caterpillar recommends a manual regeneration (or parked
regeneration). If the DPF Lamp and Check Engine Lamp do not
go out after a complete manual regeneration, contact your
authorized Caterpillar ® dealer.
The HEST Lamp comes on when the vehicle speed
is less than 5 mph and the DPF outlet temperature
is more than approximately 840º F (450º C). This
condition can occur under normal operation. No
action is required.
Engine Noise: If the truck shuts down during a regeneration, the
CRS purge air pump will run for approximately 10 minutes. When
key is on at truck startup, the air pump will run for approximately
five minutes. This is normal operation of the pump.
Manual Regeneration (or Parked Regeneration)
For a manual regeneration, all of the following conditions must
be met.
a.The DPF Lamp must be on or is flashing with the Inhibit
(or Disable) Switch “off.”
b.The Manual Regeneration (or Parked Regeneration)
switch must be enabled or “on.”
c.The throttle, clutch and service brake must
be released.
d. Vehicle speed must be zero.
e. The automatic transmission must be
in neutral.
f. The parking brake must be set, if programmed.
When these conditions are met and the switch is on (for some
OEMs the switch is depressed for four seconds), the DPF
Lamp turns off and the engine speed automatically increases
to between 1200 rpm and 1400 rpm. Once the DPF reaches
approximately 840° F (450° C), the High Exhaust System
Temperature (HEST) Lamp illuminates. When regeneration is
complete, the engine returns to idle.
If any of the above conditions change, manual regeneration
deactivates and the engine returns to idle. If the DPF Lamp
illuminates again, manual regeneration must be restarted.
HEST (High Exhaust
System Temperature)
DPF (Diesel Particulate
Filter) Lamp
Check Engine Lamp
Stop Engine Lamp
Note: This information is for reference only.
Consult the Caterpillar Engine Operation and Maintenance
Manual or your OEM truck manufacturer’s manual for
a complete description of exhaust aftertreatment.
© Caterpillar 2007. All rights reserved. CAT, CATERPILLAR, their respective logos, ACERT,
“Caterpillar Yellow” and the POWER EDGE trade dress, as well as corporate and product
identity used herein, are trademarks of Caterpillar and may not be used without permission.
LEDT 7022
Soot loading is an accumulation of particulate
matter in the DPF. During normal operation, the
lamps should not come on, but there may be
circumstances when they do. Following is a brief
summary of what the lamps mean and what to
do if they should light up. If the lamps remain on
after the recommended actions, contact your
Caterpillar authorized dealer.
5.If the vehicle continues to be driven without
regeneration, the engine progressively derates
down to a reduced horsepower level which will
limit maximum vehicle speed.
6.At Level 4 of soot loading, the Stop Engine
Lamp comes on. If regeneration is not started
immediately, the Stop Engine Lamp will begin to
flash and the engine will shut off in 30 seconds.
(If Equipped)
The switches pictured are for example only. They may or
may not appear on your vehicle’s dashboard; every truck
manufacturer uses a different arrangement. For specific
instruction, consult your OEM truck manufacturer’s manual.
Three Position Switch
Front View
7.The engine may be restarted and the driver
must initiate regeneration. If the vehicle
continues to be driven without regeneration, the
engine shuts down for a second time.
Soot Level
8.After a second shutdown, regeneration may not
be initiated and the engine will run for only 60
seconds at a time.
Soot Loading
1.If the DPF Lamp begins to flash, check to ensure
the two position Inhibit (or Disable) switch
is “off” or the three position switch is in the
automatic regeneration position. The DPF Lamp
will stop flashing when the Inhibit (or Disable)
function is “off.” If the DPF Lamp continues to
flash, proceed to step 3.
2. The DPF Lamp comes on when the DPF reaches
Level 1 of soot loading.
3. I f the vehicle continues to be driven, the
DPF will reach Level 2 of soot loading and
the DPF Lamp will begin to flash or turn red.
A regeneration must be performed as soon
as safely possible.
4.The DPF Lamp continues to flash and the Check
Engine Lamp comes on when soot loading
reaches Level 3. Regeneration is required.
Side Views
UP: Start
MIDDLE: Automatic
Inhibit (or Disable)
Function is “on”
Two Position Manual/Parked
Regeneration Switch
Front View
Side View
(If Equipped)
The dash switch allows the driver to control the
regeneration process.
1. A
utomatic (Preferred Position): A regeneration cycle starts
automatically when engine conditions warrant. The driver
does not need to take any action.
2. Disabled or Inhibit: Engaging this switch stops the
regeneration process.
Regeneration is “on”
Two Position Switch - Inhibit or Disable Regeneration*
Front View
Side View
aution: The DPF and regeneration system may be
damaged if this switch remains in this position for an
extended time.
3. Manual Regeneration (or Parked Regeneration) Start: The
driver can initiate regeneration by moving the switch to the
“on” position. Some OEM switches require the switch to be
held for four seconds. The DPF Lamp must be on or flashing
for manual regeneration to occur..
Inhibit (or Disable)
Function is “on”
Inhibit (or Disable)
Function is “off”
*The Disable Switch overrides the Manual Regeneration Switch. For Manual
Regeneration to occur, the Disable Switch must be in the Automatic
Regeneration position (OFF). For automatic regeneration to occur both the
Disable and Manual Regeneration switches must be in the off position.
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