19NA114

Service Bulletin
Bulletin No.:
19-NA-114
Date:
May, 2019
INFORMATION
Subject:
Information on Malfunction Indicator Lamp (MIL) Illuminated - DTC P0171 Set
This Bulletin replaces PIP5197M. Please discard PIP5197M.
Model Year:
VIN:
Brand:
Model:
Buick
Encore
2013
2019
Cadillac
ELR
2014
2017
Cruze
2011
2016
Sonic
2012
2019
Trax
2013
2019
Volt
2012
2015
Chevrolet
from
to
from
to
Engine:
Transmission:
1.4L (LUJ,
LUU, LUV)
Involved Region or Country
North America
Condition
Some customers may comment that the MIL is illuminated.
Some technicians may find DTC P0171 (Fuel Trim System Lean) or other airflow related
codes set in the Engine Control Module (ECM).
Cause
Information
Copyright 2019 General Motors LLC. All Rights Reserved.
This condition may be caused by a torn positive crankcase ventilation (PCV) Crankcase
Pressure Control Diaphragm.
⇒ The PCV crankcase pressure control diaphragm in the PCV valve could be
torn, allowing un-metered air to enter the crankcase.
Following the diagnostics in SI for that DTC may lead to the PCV system as a potential
source of external airflow.
Confirmation of the PCV valve performance must be done before replacing the camshaft
cover.
Page 2
May, 2019
Service Procedure
Bulletin No.: 19-NA-114
3. With the engine running, listen for noise coming
from the PCV valve.
⇒ If noise is heard, check to see if the noise gets
quieter or disappears with the engine oil
dipstick removed.
4. Reinsert the dipstick.
Note: Normal operation of the PCV crankcase
pressure control diaphragm could cause a tissue to
flutter against the port (smoke would not be
continuously drawn into the port). A torn crankcase
pressure control diaphragm would cause the tissue to
be held against the port (smoke would be continuously
drawn in) due to internal engine vacuum leaking
through the diaphragm.
5335015
Test to confirm a tear in the PCV valve:
1. Remove the engine cover. Refer to Engine Cover
Replacement in SI.
2. Verify that the engine oil dipstick is fully seated,
and the oil fill cap is fully tightened.
Version
1
Modified
Released May 15, 2019
5. Check to see if there is vacuum at the PCV vent at
the front of the PCV valve by placing a piece of
tissue near it.
⇒ The tissue will be sucked against the vent and
held if vacuum is present. Smoke can also be
used to see if it is drawing into the PCV
vent port.
• If the PCV valve is making noise and there is
vacuum present at the PCV valve vent, replace
the camshaft cover. Refer to Camshaft Cover
Replacement in SI.
• If the PCV valve does NOT make noise or leak
vacuum, the PCV system is not the cause and
further diagnostics using SI would be needed.
6. Reinstall the engine cover. Refer to Engine Cover
Replacement in SI.
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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