21NA006

Bulletin No.:
Service Bulletin
Date:
21-NA-006
January, 2021
INFORMATION
Subject:
Diagnostic Tip to Diagnose Emission Reduction Fluid Tank Electrical Connector
Inspection, Reduced Power Message, Service Emissions System, System Displayed
on the Drivers Information Center (DIC) Malfunction Indicator Lamp (MIL) Illuminated DTC P02C1, P21DD, P221C, P10D9, P10F3, P143C, P20B9, and/or P221E
Model Year:
VIN:
Brand:
Model:
Cadillac
Escalade Models
2021
LM2
Silverado 1500
2020
LM2
Chevrolet
Silverado 2500HD/
3500HD
2020
L5P
Suburban
2021
Sierra 1500
2020
LM2
Sierra 2500HD/
3500HD
2020
L5P
Yukon Models
2021
LM2
GMC
from
to
2021
from
to
Engine:
Transmission:
LM2
Involved Region or Country
North America, Uzbekistan, Russia, Middle East, Israel, Palestine, Chile (West),
Colombia (West), Ecuador (West), Paraguay (West), Peru (West), Uruguay (West),
Japan, Cadillac Korea (South Korea), Thailand (ASEAN), Australia/New Zealand
Condition
Some customers may comment that the MIL is illuminated and a reduced power message
with a Service Emissions System message as well.
Some technicians may one or more of the following DTCs set in the Engine Control
Module (ECM):
• P20C1: Reductant Heater 3 Control Circuit
• P21DD: Reductant Tank Heater 1 Low Current
• P221C: Reductant Tank Heater 2 High Current
• P10D9: Reductant Heater 1 Control Circuit Shorted
• P10F3: Reductant Heater 2 Control Circuit Shorted Reductant Heater 2 Control Circuit
• P143C: Reductant Heater 3 Control Circuit Shorted Reductant Heater 2 Control
Circuit
• P20B9: Reductant Heater 1 Control Circuit
• P221E: Reductant Tank Heater 3 Low Current
Some technicians may also find when commanding one of the heaters on, that there is no
current, 0 amps in GDS2 or unable to command the heaters on.
Cause
This condition may be caused by a poor connection at the Emission Reduction Fluid Tank
electrical connector.
Copyright 2021 General Motors LLC. All Rights Reserved.
Page 2
January, 2021
Bulletin No.: 21-NA-006
Correction
5708899
Inspect the Emission Reduction Fluid Tank electrical connector for any signs of damage
and repair as necessary.
If this condition is not found, refer to normal SI diagnostics
Version
1
Modified
Released January 20, 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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