NHTSA ID Number: 11006353
Manufacturer Communication Number: 18-NA-115
TSB/Document Date: 2024-08-14
Summary
This service bulletin provides inspection/diagnosis/correction information on a cold start misfire and/or rough idle and DTC P0300 that may also be set.
Bulletin No.: 18-NA-115
Service Bulletin
Date: July, 2024
TECHNICAL
Subject:
Cold Start Misfire and/or Rough Idle – DTC P0300 May Be Set
This Service Bulletin replaces PIP4959G. Please discard all versions of PIP4959.
Brand:
Model:
Model Year:
From
From
2025
3.6L (LLT, LFY)
Regal
2018
2019
3.6L (LGX)
LaCrosse
Allure
2009
2009
2019
2011
3.0 (LF1, LFW)
3.6 (LFX, LLT)
ATS
2013
2019
3.6 (LFX, LF4,
LGX)
CTS
2010
2019
3.0 (LF1, LFW)
3.6 (LF3, LFX,
LLT, LGX)
CT5
2020
2025
3.0 (LGY)
CT6
2016
2020
3.6 (LGW, LGX)
SRX
2010
2016
2.8 (LAU)
3.0 (LF1, LFW)
3.6 (LFX, LLT)
XTS
2013
2019
3.6 (LF3, LFX)
XT5
2018
XT6
2020
Blazer
2019
Captiva Sport
All
2025
2012
3.6 (LGX)
3.6 (LGX)
3.6 (LFX, LLT,
LGX)
2010
2017
3.6 (LFX)
2015
3.0 \(LF1, LFW)
Colorado
2015
2025
3.6 (LFX, LGZ)
Equinox
2010
2017
3.0 (LF1, LFW)
3.6 (LFX, LLT)
Impala
2012
2019
3.6 (LFX)
Traverse
2009
Acadia
2007
Canyon
Terrain
Copyright 2024 General Motors
. All Rights Reserved.
To
2009
Caprice PPV
To
Enclave
Camaro
VIN:
3.6 (LLT, LFY)
2025
3.6 (LLT, LGX)
2015
3.6 (LFX, LGZ)
2010
2017
3.0 (LF1, LFW)
3.6 (LFX, LLT)
All
Page 2
July, 2024
Bulletin No.: 18-NA-115
Involved Region or Country
North America, Argentina, Brazil, Bolivia, Colombia, Ecuador, Paraguay, Peru, Uruguay,
Venezuela, Europe, Uzbekistan, Middle East, Iraq, Israel, Japan, Cadillac Korea (South
Korea), China, Taiwan, Thailand, Singapore, Philippines
Condition
Some customers may comment that during a cold start, the engine will misfire and/or
have a rough idle and the Malfunction Indicator Lamp (MIL) may be illuminated. They
may also comment that the condition goes away after the engine warms up. The technician may observe on a scan tool DTC P0300 (Engine Misfire Detected) set in the K20
Engine Control Module.
Cause
Possible engine cylinder block porosity causing a pinhole at the liner to deck face casting
area, allowing engine coolant to leak into the affected cylinder. The technician may
observe on a scan tool DTC P0300 Engine Misfire Detected set in the K20 Engine Control Module.
Correction
Inspect for the cause of this condition by performing the Service Procedure below.
Service Procedure
Important: Service agents must comply with all
International, Federal, State, Provincial, and/or
Local laws applicable to the activities it performs
under this bulletin, including but not limited to
handling, deploying, preparing, classifying,
packaging, marking, labeling, and shipping
dangerous goods. In the event of a conflict
between the procedures set forth in this bulletin
and the laws that apply to your dealership, you
must follow those applicable laws.
1. A misfire on cold start up only and/or a rough idle
with medium to high misfire counts, always
occurring on one or two cylinders, with the
condition going away after the engine warms up
can be suspect for coolant entry at the liner to
deck face casting. To inspect for the location of the
possible cause of the condition, add coolant dye to
the engine cooling system.
2. Run the engine through a complete operating
temperature warm up (the thermostat should be
fully open at 107°C (225°F).
3632858
3. Pressurize the cooling system on a cold soak
engine (after being warmed up to operating
temperature).
4. Inspect the suspect cylinder(s) with a blacklight
borescope for evidence of the coolant dye.
5. It may be difficult to see the actual source (e.g., a
pin hole) but the leaking coolant will usually stream
down the liner so that it can be seen with a
borescope. Do not confuse residual fuel on the
piston crown/surface as engine coolant.
⇒
If the borescope inspection is inconclusive, it
may be necessary to remove the cylinder head
for further visual inspection.
6. With the cylinder head removed, perform a visual
inspection. Reference the following pictures
provided. The first two pictures represent normal
examples of deck pitting and are not the cause of
the misfire and/or rough idle condition.
3632860
7. The two following pictures represent an example
and the location of how actual engine cylinder
Bulletin No.: 18-NA-115
July, 2024
block porosity appears. This would be a cause of
the condition.
Page 3
Shown at the deck face to cylinder liner interface
location is an area of engine cylinder block porosity
that has caused an engine coolant leak path into
the cylinder, causing medium to high misfire counts
when the engine is cold.
⇒
If this condition is verified, the engine must be
replaced.
Dealers required to contact the Product Quality Center
(PQC) should refer to: Service Bulletin 20-NA-138
(U.S.) or 16-NA-338 (Canada): Warranty Administration
– Engine and Transmission Assembly Replacement in
SI and reference this Corporate Bulletin.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
4067490
Engine Replacement
Use Published
Labor Operation
Time
3632865
3632864
Version Information
Version
5
Modified
Released April 13, 2018
Revised October 01, 2018 – Added certain Model Year 2016-2019 vehicles and engine
RPO LFY, LGX and LGZ.
Revised September 02, 2020 – Added the 2020 and 2021 Model Years and 2019-2021
Blazer, 2020-2021 CT5, 2016-2020 CT6, 2019-2021 XT5, 2021 XT6 models, updated the
Involved Region or Country section and updated the PQC Bulletin references at the end
of the Service Procedure.
Revised May 02, 2022 – Added the 2018-2019 Buick Regal and 2022 Model Year for certain vehicles and updated the Involved Region or Country section.
Revised July 23, 2024 – Added the 2023-2025 Model Years to certain vehicles.
Page 4
July, 2024
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.
Bulletin No.: 18-NA-115
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TSB/Document ID: 18-NA-115
Replacement Service Bulletin Number:
MFR Communication Date: 2024-07-23
MFR Internal Campaign ID/Software Version:
Communication Type: Service Bulletin/Repair Instructions
NHTSA Components: ENGINE
MFR Component System:
MFR Component Subsystem:
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