AutoCodes – GMC – P20BB 2018 GMC Sierra

P20BB 2018 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 2018 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 250

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 2018 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 2018 GMC Sierra - Reductant Heater 1 Control Circuit Low Voltage - AutoCodes.com — P20BB 2018 GMC Sierra Code - Reductant Heater 1 Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P20BB 2018 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 2018 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 2018 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 2018 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 2018 GMC Sierra Code

1. What are common symptoms of OBDII code P20BB in a 2018 GMC Sierra related to Reductant Heater 1 Control Circuit Low Voltage?

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

2. What are the possible causes of OBDII code P20BB in a 2018 GMC Sierra indicating Reductant Heater 1 Control Circuit Low Voltage?

- Possible causes include a faulty reductant heater control module, damaged wiring or connectors, or a malfunctioning reductant heater.

3. How can I diagnose OBDII code P20BB in a 2018 GMC Sierra associated with Reductant Heater 1 Control Circuit Low Voltage?

- Diagnosis involves using an OBDII scanner to retrieve the code, checking the reductant heater system for any visible damage, and testing the heater control module and related components.

4. Can OBDII code P20BB in a 2018 GMC Sierra indicating Reductant Heater 1 Control Circuit Low Voltage be fixed at home?

- While simple issues like loose connections may be fixable at home, diagnosing and repairing more complex issues with the reductant heater system may require professional assistance.

5. Are there any DIY repair tips for addressing OBDII code P20BB in a 2018 GMC Sierra related to Reductant Heater 1 Control Circuit Low Voltage?

- DIY repair tips may include checking and tightening all electrical connections related to the reductant heater system, as well as inspecting for any visible signs of damage.

6. What are the potential risks of ignoring OBDII code P20BB in a 2018 GMC Sierra connected to Reductant Heater 1 Control Circuit Low Voltage?

- Ignoring this code may lead to reduced fuel efficiency, increased emissions, and potential damage to other components of the emissions control system over time.

7. How much does it typically cost to repair OBDII code P20BB on a 2018 GMC Sierra due to Reductant Heater 1 Control Circuit Low Voltage?

- The cost of repair can vary depending on the specific issue, but it may range from a simple fix like tightening connections to a more involved repair involving replacement of components.