NHTSA ID Number: 10187767
Manufacturer Communication Number: 21NA002
Summary
This informational bulletin provides a test procedure, for a possible faulty DEF Heater.
13 Affected Products
Vehicles
| MAKE | MODEL | YEAR |
CADILLAC | ESCALADE | 2021 |
| CADILLAC | ESCALADE ESV | 2021 |
| CHEVROLET | SILVERADO 1500 | 2020-2021 |
| CHEVROLET | SILVERADO 2500 | 2020-2021 |
| CHEVROLET | SUBURBAN | 2021 |
| GMC | SIERRA 1500 | 2020-2021 |
| GMC | SIERRA 2500 | 2020-2021 |
| GMC | YUKON | 2021 |
| GMC | YUKON XL | 2021 |
SEOCONTENT-START
Service Bulletin Bulletin No.: 21-NA-002
Date: January, 2021
INFORMATION
Subject: Diagnostic Tip to Diagnose Emission Reduction Fluid Tank Heater Element Exposed to
Diesel Exhaust Fluid (DEF) , Service Emission System/Service Exhaust Fluid System
Displayed on the Driver Information Center (DIC), Malfunction Indicator Lamp (MIL)
Illuminated – DTC P20BB and/or P20C3 Set
Brand: Model:
Model Year: VIN:
Engine: Transmission:
from to from to
Cadillac Escalade 2021
2021
LM2
Chevrolet
Silverado 1500 2020 LM2
Silverado 2500HD/
3500HD 2020 L5P
Suburban 2021 LM2
GMC
Sierra 1500 2020 LM2
Sierra 2500HD/
3500HD 2020 L5P
Yukon 2021 LM2
Involved Region or Country North America
Condition
Some customers may comment that the MIL is illuõminated with or without a “Service
Emission System/Service Exhaust Fluid System” message.
Some technicians may one or more of the following DTCs set in the Engine Control
Module (ECM):
• P20BB: Reductant Heater 1 Control Circuit Low Voltage
• P20C3: Reductant Heater 3 Control Circuit Low Voltage Test Status
Cause This condition may be caused by a faulty Emission Reduction Fluid Tank heater.
Correction
Note: If the technician finds code P20BB and/or P20C3, the following procedure can be
used to identify an issue with the Emission Reduction Fluid Tank heater
The following procedure may be useful to identify if the heater element is exposed to DEF
fluid
Service Procedure
Important: Ensue that the Emission Reduction Fluid
Tank has enough fluid in it to cover the heaters before
performing the resistance measurement.
1. Turn the vehicle off.
2. Disconnect the Emission Reduction Fluid Tank
Reservoir Wire Harness.
Page 2 January, 2021 Bulletin No.: 21-NA-002
5701194
3. Utilizing a DVOM, measure resistance from pin 9
(1) to pin 14 (3) of the Emission Reduction
Fluid Tank.
4. Measure resistance on pin 10 (2) to pin 14 of the
Emission Reduction Fluid Tank.
• If either resistance readings are less than 10M
ohm, the heater is faulty.
• If both resistance readings are greater than
10M ohm, refer to SI for further diagnostics.
Version 1
Modified Released January 13, 2021
SEOCONTENT-END
1 Associated Document
Manufacturer Communications
Bulletin No.: 21-NA-002
Date: January, 2021
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