Engine-CodesGMC – P20BC 2017 GMC Sierra

P20BC 2017 GMC Sierra Code - Reductant Heater 1 Control Circuit High Voltage

Quick Answer

The P20BC diagnostic trouble code (DTC) for a 2017 GMC Sierra relates to the Reductant Heater 1 Control Circuit High Voltage. Common causes include Faulty Control Module: A malfunctioning control module can cause high voltage in the reductant heater control circuit, Short Circuit: Wiring issues or a short circuit in the control circuit can trigger this code, Defective Reductant Heater: A malfunctioning reductant heater itself can cause high voltage in the control circuit. 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 2017 GMC Sierra indicates Reductant Heater 1 Control Circuit High Voltage.
Common causes
Common causes include Faulty Control Module: A malfunctioning control module can cause high voltage in the reductant heater control circuit, Short Circuit: Wiring issues or a short circuit in the control circuit can trigger this code, Defective Reductant Heater: A malfunctioning reductant heater itself can cause high voltage in the control circuit.
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.
Table of contents Created and updated by William Orellana on Sep 13, 2024
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Code P20BC 2017 GMC Sierra Description

The P20BC diagnostic trouble code (DTC) for a 2017 GMC Sierra relates to the Reductant Heater 1 Control Circuit High Voltage. This code indicates that there is a problem with the control circuit for the reductant heater, which is a component of the selective catalytic reduction (SCR) system in the vehicle. The reductant heater is responsible for heating the diesel exhaust fluid (DEF) to optimize its performance in reducing harmful emissions.

OBDII Code P20BC 2017 GMC Sierra - Reductant Heater 1 Control Circuit High Voltage
P20BC 2017 GMC Sierra Code - Reductant Heater 1 Control Circuit High Voltage

Common Causes of P20BC 2017 GMC Sierra

  1. Faulty Control Module: A malfunctioning control module can cause high voltage in the reductant heater control circuit.
  2. Short Circuit: Wiring issues or a short circuit in the control circuit can trigger this code.
  3. Defective Reductant Heater: A malfunctioning reductant heater itself can cause high voltage in the control circuit.
  4. Corroded Connectors: Corrosion or poor connections in the wiring harness can lead to electrical issues in the control circuit.

Symptoms of P20BC 2017 GMC Sierra

  1. Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced DEF Heating: The reductant heater may not heat the DEF fluid efficiently, leading to increased emissions and reduced performance.
  3. Poor Fuel Efficiency: A malfunctioning reductant heater can impact the vehicle's fuel efficiency, resulting in more frequent refills of DEF.
  4. Failed Emissions Test: If the issue is not addressed, it can cause the vehicle to fail emissions tests due to increased emissions output.

How to Fix P20BC 2017 GMC Sierra

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the DTC and pinpoint the exact cause of the high voltage in the reductant heater control circuit.
  2. Inspect Wiring and Connectors: Check the wiring harness and connectors for any signs of damage, corrosion, or loose connections.
  3. Test Control Module: Test the control module for proper functionality and replace if necessary.
  4. Replace Reductant Heater: If the reductant heater is found to be defective, replace it with a new unit.
  5. Clear Codes and Test: After completing the repairs, clear the DTC and test the vehicle to ensure the issue has been resolved.

Cost to Fix P20BC 2017 GMC Sierra

The typical repair costs for addressing a P20BC code on a 2017 GMC Sierra can range from $200 to $600, including parts and labor. However, it's important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Most auto repair shops charge between $80 and $150 per hour for labor, but rates may be higher in metropolitan areas or at dealerships, while independent shops may offer lower rates. It's recommended to inquire about local rates for a more accurate estimate.

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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.

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