AutoCodes – GMC – P20BB 2017 GMC Sierra

P20BB 2017 GMC Sierra Code - Reductant Heater 1 Control Circuit Low Voltage

Quick Answer

As reductant will freeze at temperatures below -11°C (12°F), there are 2 reductant heaters located in the reductant tank. Common causes include Faulty Reductant Heater, Reductant Heater harness is open or shorted, Reductant Heater circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P20BB 2017 GMC Sierra indicates Reductant Heater 1 Control Circuit Low Voltage.
Common causes: Common causes include Faulty Reductant Heater, Reductant Heater harness is open or shorted, Reductant Heater circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 119

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 29, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P20BB 2017 GMC Sierra Description

As reductant will freeze at temperatures below -11°C (12°F), there are 2 reductant heaters located in the reductant tank. One heats the reductant in the tank, and one heats the reductant supplied to the reductant injector supply pipe. The Engine Control Module (ECM) monitors the reductant temperature in the tank in order to determine if the reductant temperature is below its freeze point. If the ECM determines that the reductant may be frozen, it activates a "defrost strategy" energizing the reductant eater. This energizing action terminates when the temperature sensor measures a threshold value over which the heater must be deactivated.
The Diagnostic Trouble Code (DTC) will be set when the ECM indicates the reductant tank heater control circuit is shorted to ground or overloaded for greater than 4 s.

OBDII Code P20BB 2017 GMC Sierra - Reductant Heater 1 Control Circuit Low Voltage - AutoCodes.com — P20BB 2017 GMC Sierra Code - Reductant Heater 1 Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P20BB 2017 GMC Sierra?

Faulty Reductant Heater
Reductant Heater harness is open or shorted
Reductant Heater circuit poor electrical connection
Faulty Reductant Pump and Sensor Assembly
Faulty Reductant Control Module

How to Fix the DTC P20BB 2017 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P20BB 2017 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P20BB 2017 GMC Sierra code?

Need more information on how to fix the P20BB 2017 GMC Sierra code? Get Access to Factory Service Manuals

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P20BB 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code P20BB in a 2017 GMC Sierra?

- Common symptoms include the check engine light coming on, reduced engine performance, and potential issues with the exhaust system.

2. What does the OBDII code P20BB for a 2017 GMC Sierra indicate?

- The code P20BB indicates a problem with the Reductant Heater 1 Control Circuit Low Voltage in the vehicle's selective catalytic reduction (SCR) system.

3. What are the possible causes of OBDII code P20BB in a 2017 GMC Sierra?

- Possible causes include a faulty reductant heater, damaged wiring or connectors, a defective SCR control module, or issues with the power supply to the reductant heater.

4. How can I diagnose the OBDII code P20BB in my 2017 GMC Sierra?

- Diagnosis typically involves using a scan tool to retrieve the code, checking the system for any visible damage or loose connections, and testing the components involved in the reductant heater system.

5. Can I continue driving my 2017 GMC Sierra with the OBDII code P20BB?

- It is not recommended to continue driving with the code active, as it can lead to increased emissions, reduced fuel efficiency, and potential damage to the engine or emissions system.

6. How do I repair OBDII code P20BB in a 2017 GMC Sierra?

- Repair may involve replacing the reductant heater, repairing or replacing damaged wiring or connectors, resetting the code, and performing a thorough inspection of the SCR system.

7. Is it possible to reset the OBDII code P20BB in a 2017 GMC Sierra without repairing the issue?

- While you can clear the code with a scan tool, it is important to address the underlying problem causing the code to prevent further issues down the line.

8. Can a DIY enthusiast fix the OBDII code P20BB in a 2017 GMC Sierra?

- Depending on your level of automotive expertise, you may be able to diagnose and repair the issue yourself, but it is recommended to consult a professional mechanic for accurate diagnosis and repair.

9. How long does it typically take to repair OBDII code P20BB in a 2017 GMC Sierra?

- The repair time can vary based on the exact cause of the code, but it may take a few hours to a full day to diagnose and repair the issue properly.

10. Are there any preventive measures to avoid OBDII code P20BB in a 2017 GMC Sierra?

- Regular maintenance checks, such as inspecting the SCR system components and ensuring proper operation, can help prevent issues that may trigger the code P20BB.