18-NA-115

Service Bulletin
Bulletin No.:
18-NA-115
Date:
May, 2022
TECHNICAL
Subject:
Cold Start Misfire and/or Rough Idle – DTC P0300 May Be Set
This bulletin replaces PIP4959G. Please discard all versions of PIP4959.
Brand:
Buick
Cadillac
Chevrolet
Model:
Model Year:
VIN:
From
To
Engine:
From
To
Enclave
2009
2022
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
2022
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
XT5
2018
2022
XT6
2020
2022
Blazer
2019
2022
3.6 LGX
Camaro
2010
2022
3.6 LFX,
LLT, LGX
Caprice PPV
2012
2017
3.6 LFX
Captiva
Sport
2012
2015
3.0 LF1, LFW
Colorado
2015
2022
3.6 LFX, LGZ
Equinox
2010
2017
3.0 LF1, LFW,
3.6 LFX, LLT
Impala
2012
2019
3.6 LFX
Traverse
2009
2022
3.6 LLT, LFY
Copyright 2022 General Motors LLC. All Rights Reserved.
All
3.6 LF3, LFX
3.6 LGX
Transmission:
All
Page 2
Brand:
GMC
May, 2022
Model:
Model Year:
From
Bulletin No.: 18-NA-115
VIN:
To
From
To
Engine:
Acadia
2007
2022
3.6 LLT, LGX
Canyon
2015
2022
3.6 LFX, LGZ
Terrain
2010
2017
All
Transmission:
All
3.0 LF1, LFW,
3.6 LFX, LLT
Involved Region or Country
North America, Europe, Uzbekistan, Middle East, Iraq, Israel, Argentina, Brazil, Bolivia,
Colombia, Ecuador, Paraguay, Peru, Uruguay, Venezuela, 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
Notice: A black light looks dark purple, but most of
the light it emits is in the ultraviolet (UV) range of
the spectrum, which is invisible to the human eye.
Under a UV light, white clothes glow in the dark and
many fluorescent colored items (e.g., coolant dye)
will emit a bright glow.
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).
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.
Bulletin No.: 18-NA-115
May, 2022
Page 3
Notice: Small surface pock marks or pitting
appearance on the deck surface is normal and an
engine should not be replaced for any such
appearance marks as they do not connect to the
engine coolant passages and cause a leak path that
will generate engine misfires.
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.
3632865
3632858
3632864
3632860
7. The two following pictures represent an example
and the location of how actual engine cylinder
block porosity appears. This would be a cause of
the condition.
Notice: This porosity condition is rare, therefore
the technician should inspect the suspect
cylinder(s) and look for a break/pinhole in the
carbon ring area.
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.
Page 4
May, 2022
Bulletin No.: 18-NA-115
Warranty Information
For vehicles repaired under warranty, use:
Labor
Operation
Description
Labor Time
4067490
Engine Replacement
Use Published
Labor
Operation Time
Version Information
Version
4
Modified
Released April 13, 2018
October 01, 2018 – Added certain Model Year 2016-2019 vehicles and engine RPO LFY,
LGX and LGZ.
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.
May 02, 2022 – Added the 2018-2019 Buick Regal and 2022 Model Year for certain
vehicles 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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