Service Bulletin

Bulletin No.:

21-NA-215

Date:

July, 2022

TECHNICAL
Subject:

Pop Noise Heard on Heavy Acceleration Only, Lack of Power When on the Highway,
Stall- Multiple DTC’s or No DTC’s Set

Brand:

Model:

Buick

Encore GX

Chevrolet

Trailblazer
(VIN M)

Model Year:

VIN Breakpoint:

from

to

from

2021

2022

SOP

to

Engine:

Transmission:

KL4MMBS20NB085427
KL79MUSL5NB082536

LIH, L3T

Involved Region or Country

North America

Condition

Some customers may comment that a pop noise can be heard on heavy acceleration
from the engine area.
Some technicians may find NO DTCs, or one or more of the following DTCs set:
• ABS U0100:Lost Communication with Engine Control Module
• ABS U0140: Lost Communication with Body Control Module
• ABS U026A:Lost Communication with Frontview Camera Module
• ABS C2A07:Engine Control Module Indicated Torque Interface Failed
• BCM U0100:Lost Communication with Engine Control Module
• ABS U0151:Lost Communication with Restraints Control Module
• ABS C0501:Steering Assist Control Actuator Return Circuit
• ABS P0606:Control Module Processor Performance
• ECM U1346:Engine Control Module LIN Bus 2
• ECM U060F:Lost Communication with Mass Air Flow (MAF) Sensor Bank 1
• ECM P0102:Mass Air Flow (MAF) Sensor Circuit Low
• ECM P0352:Ignition Coil 2 Control Circuit
• ECM P0300:Engine Misfire Detected
• ECM P0351:Ignition Coil 1 Control Circuit
• ECM P228C:Fuel Pressure Regulator 1 Exceeded Control Limits - Pressure Too Low
• ECM P25A2:Brake System Control Module Requested MIL Illumination
• EPS U0415:Invalid Data Received From Antilock Brake System Control Module
If no DTCs are set the technician may also find:
• GDS Engine Control Module (ECM) data shows Cylinder Knock Detected in all three
cylinders.
• All Ignition Coil Control Circuit High Voltage Test Status display ‘Malfunction’ when
condition was present around 5k rpm under load.

Copyright 2022 General Motors LLC. All Rights Reserved.

Page 2

July, 2022

Bulletin No.: 21-NA-215

Cause

5420987

G106 LIH ground wire location

Bulletin No.: 21-NA-215

July, 2022

Page 3

5925499

G106 L3T ground wire location
This condition may be caused by a loose ground located at G106 (1).
– The G106 ground nut may not have been tighten to specifications from the factory.
Correction

Locate the G106 ground. Inspect the stud and replace if needed, then tighten nut.

Parts Information
No parts are required for this repair.

Warranty Information
For vehicles repaired under the Bumper-to-Bumper
coverage (Canada Base Warranty coverage), use the
following labor operation. Reference the Applicable
Warranties section of Investigate Vehicle History (IVH)
for coverage information.
Labor Operation

Description

Labor Time

5486248*

Replace Stud and Tighten G106 Ground

0.5 hr

*This is a unique Labor Operation for Bulletin use only.

Page 4

July, 2022

Bulletin No.: 21-NA-215

Version

4

Modified

Released September 24, 2021
Revised November 19, 2021 – Updated subject, added additional engine RPO, updated
Condition Section, Correction Section, and Warranty Information Section labor operation
description, added additional graphic
Revised February 03, 2022 - Added Date to Date Breakpoint section.
Revised July 25, 2022 - Add VIN to VIN Breakpoint 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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