Cold Start Rough Run, Misfire and/or Malfunction Indicator Lamp (MIL) Illuminated – 2017-2019 Chevrolet Silverado & GMC Sierra

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Service Bulletin Bulletin No.: 19-NA-108
Date: June, 2019
TECHNICAL
Subject: Cold Start Rough Run, Misfire and/or Malfunction Indicator Lamp (MIL) Illuminated
Brand: Model:
Model Year: VIN:
Engine: Transmission:
from to from to
Chevrolet
Silverado 2017 2018
L5P
Silverado
2500/3500 2019 2019
GMC
Sierra 2017 2018
Sierra
2500/3500 2019 2019
Involved Region or Country North America, N.A. Export Markets and Israel
Condition
Some customers may comment on one or more of the following conditions:
• Engine runs rough during cold stars, but smooths out when warmed up
• Engine misfires
• MIL illuminated
Some technicians may find injector timing related DTCs on ONE bank of the engine.
Cause This condition may be caused by two head gaskets being installed on one bank of the
engine.
Correction
Important: The vehicle must have more than 2000 miles (3219 km) since new or the
latest fuel injector replacement.
Page 2 June, 2019 Bulletin No.: 19-NA-108
5336396
Inspect for two head gasket tabs on the driver’s side front of the engine (as shown) or on
the passenger’s side rear of the engine. A bore scope or inspection mirror may be used
between the power steering pump bracket and engine. Inspecting the passenger’s side
head gasket tab(s) can be made easier from underneath with the vehicle on a lift and a
bore scope.
⇒ If two head gaskets on one bank of the engine is confirmed, during removal,
please try to keep the two gaskets together as an assembly. DO NOT try to
separate them. Engineering would like these kept together for analysis.
Install a new head gasket with the same grade that was removed.
Service Procedure
Note: Prior to installing the rocker arm shaft, loosen all
rocker arm adjustment nuts AND unscrew the adjuster.
This will help prevent piston to valve contact and
potential damage to the pushrods.
Replace the affected cylinder head gasket with the
same grade that was removed. Refer to Cylinder Head
Replacement – Left Side or Cylinder Head
Replacement – Right Side in SI.
Parts Information
Causal
Part
Description Part
Number
Qty
X GASKET, CYL HD Refer
to EPC
1
Bulletin No.: 19-NA-108 June, 2019 Page 3
Warranty Information
Note: Only select the Labor Operation that coincides
with the repair performed.
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
4061670 Cylinder Head Gasket Replacement – Right Side
Use the Published Labor
4061690 Cylinder Head Gasket Replacement – Left Side Operations Time
4061731 Cylinder Head Gasket Replacement – Both Banks
Version 2
Modified
Released May 16, 2019
Revised June 25, 2019 – Added additional keywords.
Additional Keywords: Coolant Leak, Coolant, Leak

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