21NA257

Bulletin No.:
Service Bulletin
Date:
21-NA-257
December, 2021
TECHNICAL
Subject:
Malfunction Indicator Lamp (MIL) Illuminated - DTC P3075 Set
Model Year:
Brand:
Model:
Buick
Cadillac
Chevrolet
GMC
VIN:
from
to
Engine:
(1.3L,
2.0L, 2.7L)
from
to
Encore GX
2020
2022
CT4
2020
L3B, LSY
CT5
2020
LSY
XT4
2019
XT5
2020
LSY
XT6
2020
LSY
L3T
2022
Blazer
2019
2022
Malibu
2019
2021
LSY
LSY
L3T
—
—
—
Silverado
1500 (New
Model)
2019
Silverado
1500
2020
Trailblazer
2021
Acadia
2020
2022
LSY
Sierra 1500
(New Model)
2019
2019
L3B
Sierra 1500
2020
2022
L3B
2019
2022
Transmission:
L3B
L3B
L3T
Involved Region or Country
North America, Europe, Russia, Middle East, Israel, Palestine, Chile, Colombia, Ecuador,
Paraguay, Peru, Uruguay, Japan, Cadillac Korea (South Korea), GM Korea Company,
Thailand
Condition
Some customers may comment that the MIL is illuminated.
Some technicians may find DTC P3075 (Engine Coolant Flow Too Low) set in the Engine
Control Module (ECM).
Cause
This condition may be caused by low coolant or air trapped in the cooling system.
Copyright 2021 General Motors LLC. All Rights Reserved.
Page 2
December, 2021
Bulletin No.: 21-NA-257
Note: For 2019 MY vehicles equipped with the 2.7L (L3B), refer to Service Bulletin #
19-NA-149 first to verify if the vehicle has the most current level of software.
If you encounter a vehicle with the above condition, complete the following steps:
Important: Do not replace the coolant pump assembly at this time.
1. Pressure test the cooling system to confirm no coolant leaks are present. Any leaks
in the cooling system should be repaired using Service Information.
2. Once the coolant leak has been repaired, refer to the latest Cooling System
Draining and Filling procedure in SI for coolant fill and bleeding procedures.
Note: Once the engine is started after the coolant service fill procedure, it will be
possible that DTC P3075 may reset until all the air is properly purged from the cooling
system. At this point, codes should be cleared, the engine should be at operating
temperature and the vehicle road tested to completely purge any remaining air from the
cooling system.
Correction
3. Once completed, clear any DTCs and operate the vehicle under the conditions for
running the trouble code per SI.
Note: The P3075/P3076 can detect coolant flow-based failures.
– The intrusive diagnostic test will run once per ignition cycle if all enable conditions
are met per SI. The intrusive diagnostic will run the coolant pump at roughly 4000
rpm for 15 seconds and evaluates the pump motor AC current to be within
expected range.
– The coolant pump AC current feedback will be lower if the cooling system is
leaking or low on coolant.
4. Using GDS, confirm the P3075 has run and passed in the current drive cycle to
ensure the diagnostic has executed and no fault is detected before releasing the
vehicle back to the customer.
If the vehicle returns for a second time with DTC P3075, replace the coolant pump
assembly. Parts will be returned to the Warranty Parts Center.
Parts Information
No parts are required for this repair.
Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
Labor
Operation
4087038*
Description
Labor Time
Pressure Test the Cooling
System
0.3 hr
*This is a unique Labor Operation for bulletin use only.
Version
2
Modified
Released November 12, 2021
December 14, 2021 – Added the Chevrolet Malibu model and updated the Involved
Region or Country section.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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