20NA043

Bulletin No.:
Service Bulletin
Date:
20-NA-043
November, 2020
INFORMATION
Subject:
Brand:
Chevrolet
GMC
Information on Reduced Engine Power Message Displayed on the Driver Information
Center (DIC), Malfunction Indicator Light (MIL) Illuminated - DTC P0106 and/or
P140C Set
Model:
Model Year:
from
to
Silverado
2017
2018
Silverado 2500/3500
2019
2021
Sierra
2017
2018
Sierra 2500/3500
2019
2021
VIN:
from
to
Engine:
Transmission:
L5P
Involved Region or Country
North America
Condition
Some customers may comment on one or more of the following conditions:
• Reduced engine power displayed on the DIC
• MIL Illuminated
Some technicians may find one or more of the following DTCs set in the Engine Control
Module (ECM):
• P0106: Manifold Absolute Pressure (MAP) Sensor Performance
• P140C: HO2S Slow Response Rich to Lean Sensor 1
Cause
Information
This condition may be caused by ice forming on the TMAP sensor.
Important: It is recommended to use a winter cover on 2020 model year vehicles in
temperatures below 24F (-5C).
During a 1-2 hour drive in below freezing temperatures, ice may form on the MAP sensor.
This could cause drivability issues and reduced power message along with the MIL. Once
the vehicle is stopped and allowed to idle, the ice on the sensor melts. The next key
cycle, the reduced power should be gone, but the MIL (P0106/P140C) will remain.
Important: Due to the sensitivity of the sensor, Do Not use any chemical cleaners
including water and Do Not use compressed air to remove contaminates.
If P0106 is set in history and there is evidence that the code may have set due to icing,
inspect the TMAP sensor. If it is clean and dry, there is no need to replace the sensor.
Installing a winter grill cover may reduce the possibility of future occurrences. Please note
on the repair order if a winter grill cover was on the vehicle when it arrived.
Important: If sensor is covered in soot, this should not prevent the sensor from
functioning properly and it should not be replaced. Do not attempt to clean soot off the
sensor. This could cause damage to the Thermistor
Copyright 2020 General Motors LLC. All Rights Reserved.
Page 2
November, 2020
Bulletin No.: 20-NA-043
Parts Information
No parts are required for this repair.
Version
3
Modified
Released February 26, 2020
Revised May 04, 2020 - Add Important statement to install a winter cover in Information
section.
Revised October 27, 2020 - Add 2021 Model Year.
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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