Malfunction Indicator Lamp (MIL) Illuminated with DTC P26BB Set – 2019-2022 Buick Cadillac Chevrolet GMC

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Copyright 2021 General Motors LLC. All Rights Reserved.
Service Bulletin Bulletin No.: 21-NA-256
Date: November, 2021
TECHNICAL
Subject: Malfunction Indicator Lamp (MIL) Illuminated with DTC P26BB Set
Brand: Model:
Model Year: VIN:
Engine: Transmission:
from to from to
Buick Encore GX 2019
2022 — —
1.3 (L3T)
—
Cadillac
CT4
2020 2.0 (LSY) and
CT4-V 2.7L (L3B)
CT5
2019 2.0 (LSY)
XT4
XT5
Chevrolet Blazer
GMC Acadia
Involved Region or Country North America, Europe, Russia, Middle East, Israel, Chile, Colombia, Ecuador, Peru,
Japan, Cadillac Korea (South Korea)
Condition
Some customers may comment on a MIL illuminated in the DIC.
Technicians may find DTC P26BB set current or in recent history.
Cause The causes of the condition may be due to a break-in period of the coolant flow control
valve (CCV).
Correction
Note: For 2019 MY vehicles equipped with the 2.0L LSY, refer to Service Bulletin #
19-NA-022 first to verify the vehicle has the most current level of software.
Note: For 2019 MYand 2020 MY Chevrolet Silverado or GMC Sierra vehicles equipped
with the 2.7L L3B, refer to Service Bulletin # 20-NA-100.
Note: For 2021 MY Encore GX and Chevrolet Trailblazer 1.3L L3T, refer to Service
Bulletin # 20-K-010.
Note: For 2020 & 2021 MY Encore GX 2021 MY Chevrolet Trailblazer 1.2L LIH, refer to
Service Bulletin # 20-K-009.
Note: This code may occur on valves with low mileage/during break-in period less than
3,200 km (2000 mi). Typically, self-resolves after further valve actuations.
Check the VIN history to determine if the code has previously set in the ECM.
A. If the vehicle has set a P26BB previously, replace the Coolant Flow Control Valve.
If the vehicle has not set a P26BB previously, perform the latest SI diagnostic for
the code.
Clear any codes and return the vehicle to the customer.
B. If the code is set current, and the SI diagnostic isolates the root cause to the Coolant
Flow Control Valve, replace the valve and perform the scan tool control function:
Engine Coolant Control Valve Mode.
The value should increase and decrease according to the command in the scan tool.
Clear any codes and return the vehicle to the customer.
C. In the event that the customer returns with either DTC set a second time, replace the
valve and perform the scan tool control function: Engine Coolant Control Valve Mode.
Page 2 November, 2021 Bulletin No.: 21-NA-256
Warranty Information
Important: Warranty coverage code E (Base
Emission) applies for this Labor Operation.
For vehicles repaired under the Powertrain coverage,
use the following labor operation. Reference the
Applicable Warranties section of Investigate Vehicle
History (IVH) for coverage information.
Labor
Operation
Description Labor Time
4087438*
Complete published
diagnostics, clear DTCs and
release vehicle to customer
0.4 hr
*This is a unique Labor Operation for bulletin use only.
Version 1
Modified Released November 09, 2021
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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