AutoCodes – GMC – P20BC 2018 GMC Sierra

P20BC 2018 GMC Sierra Code - Reductant Heater 1 Control Circuit High 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: P20BC 2018 GMC Sierra indicates Reductant Heater 1 Control Circuit High 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 200

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 P20BC 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 a voltage for greater than 4 s.

OBDII Code P20BC 2018 GMC Sierra - Reductant Heater 1 Control Circuit High Voltage - AutoCodes.com — P20BC 2018 GMC Sierra Code - Reductant Heater 1 Control Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P20BC 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 P20BC 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 P20BC 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 P20BC 2018 GMC Sierra code?

Need more information on how to fix the P20BC 2018 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 P20BC 2018 GMC Sierra Code

1. What are the common symptoms of OBDII code P20BC in a 2018 GMC Sierra related to Reductant Heater 1 Control Circuit High Voltage?

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

2. What are some possible causes of OBDII code P20BC in a 2018 GMC Sierra?

- Possible causes may include a faulty reductant heater 1, damaged wiring or connectors in the control circuit, or issues with the powertrain control module.

3. How can I diagnose OBDII code P20BC in a 2018 GMC Sierra?

- Diagnosis typically involves using an OBDII scanner to retrieve the fault code, conducting a visual inspection of the reductant heater 1 and its components, and testing the control circuit for voltage irregularities.

4. Can I continue driving my 2018 GMC Sierra with OBDII code P20BC triggered?

- It is not recommended to continue driving the vehicle with this fault code active, as it may lead to poor engine performance and potential damage to the emission system components.

5. How can I repair OBDII code P20BC in a 2018 GMC Sierra myself?

- DIY repair options may include checking and replacing the reductant heater 1, repairing any damaged wiring or connectors, and clearing the fault code with an OBDII scanner.

6. Is it necessary to reset the OBDII code P20BC after repairing the issue in a 2018 GMC Sierra?

- Yes, it is important to clear the fault code after repairing the underlying issue to reset the check engine light and ensure proper functioning of the vehicle's emission system.

7. Are there any recalls or technical service bulletins related to OBDII code P20BC in a 2018 GMC Sierra?

- It is recommended to check with a GMC dealership or online resources for any relevant recalls or technical service bulletins related to this specific OBDII code in your vehicle.

8. What is the typical cost to repair OBDII code P20BC in a 2018 GMC Sierra at a professional auto repair shop?

- The cost of repairing this code can vary depending on the exact cause and the labor rates of the repair shop, but it may range from $200 to $500 or more.

9. How long does it take to repair OBDII code P20BC in a 2018 GMC Sierra?

- The repair time can vary based on the specific issue, but it typically takes anywhere from 1 to 3 hours to diagnose and fix the problem related to Reductant Heater 1 Control Circuit High Voltage.

10. Can OBDII code P20BC in a 2018 GMC Sierra be a recurring issue even after repair?

- If the underlying cause of the fault code is not properly addressed during repair, it is possible for OBDII code P20BC to reoccur. It is important to ensure thorough diagnosis and repair to prevent this from happening.