AutoCodes – GMC – P20BB 2015 GMC Sierra

P20BB 2015 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 2015 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 166

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 2015 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 2015 GMC Sierra - Reductant Heater 1 Control Circuit Low Voltage - AutoCodes.com — P20BB 2015 GMC Sierra Code - Reductant Heater 1 Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P20BB 2015 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 2015 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 2015 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 2015 GMC Sierra code?

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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 2015 GMC Sierra Code

1. What are the common symptoms of OBDII code P20BB on a 2015 GMC Sierra?

- Common symptoms include the check engine light coming on, reduced engine performance, and potential issues with the vehicle's emissions system.

2. What does the OBDII code P20BB - Reductant Heater 1 Control Circuit Low Voltage mean for a 2015 GMC Sierra?

- This code indicates that there is a low voltage condition in the control circuit of the reductant heater 1 in the vehicle's emissions system.

3. What are some possible causes of the P20BB code on a 2015 GMC Sierra?

- Possible causes include a faulty reductant heater, damaged wiring or connectors in the control circuit, a blown fuse, or issues with the vehicle's powertrain control module (PCM).

4. How can I diagnose the cause of the P20BB code on my 2015 GMC Sierra?

- Diagnosing the issue may involve performing a visual inspection of the reductant heater system, checking for damaged wiring or connectors, testing the reductant heater for proper operation, and scanning the vehicle's PCM for any related trouble codes.

5. Can I continue driving my 2015 GMC Sierra with the P20BB code present?

- It is not recommended to drive your vehicle with the P20BB code active, as it can lead to increased emissions, reduced fuel efficiency, and potential damage to the emissions system components.

6. How can I repair the P20BB code on my 2015 GMC Sierra?

- Repairing the issue may involve replacing the faulty reductant heater, repairing any damaged wiring or connectors, replacing blown fuses, or reprogramming the vehicle's PCM if necessary.

7. Are there any DIY tips for fixing the P20BB code on a 2015 GMC Sierra?

- DIY tips may include checking and cleaning the electrical connections in the reductant heater system, ensuring proper voltage supply to the heater, and following manufacturer service information for troubleshooting steps.

8. How much does it typically cost to repair the P20BB code on a 2015 GMC Sierra?

- Repair costs can vary depending on the specific cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

9. Can resetting the OBDII code P20BB on a 2015 GMC Sierra make it go away permanently?

- Resetting the code without addressing the underlying issue will not make it go away permanently. The root cause of the problem must be diagnosed and repaired to prevent the code from returning.

10. Is the P20BB code a common issue in 2015 GMC Sierra vehicles?

- While not extremely common, the P20BB code can occur in 2015 GMC Sierra vehicles, especially in cases where there are issues with the reductant heater system or related components.