Engine-CodesGMC – P20BC GMC

P20BC GMC Code - Reductant Heater 1 Control Circuit High Voltage

Quick Answer

The P20BC diagnostic trouble code for GMC vehicles specifically refers to an issue with the Reductant Heater 1 Control Circuit registering high voltage. Common causes include Faulty Reductant Heater Element: The most common cause of the P20BC code is a malfunctioning heater element within the Reductant Heater, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness associated with the Reductant Heater can trigger this code, Defective Control Module: A faulty control module responsible for regulating the Reductant Heater 1 Control Circuit can also cause high voltage issues. 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 GMC indicates Reductant Heater 1 Control Circuit High Voltage.
Common causes
Common causes include Faulty Reductant Heater Element: The most common cause of the P20BC code is a malfunctioning heater element within the Reductant Heater, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness associated with the Reductant Heater can trigger this code, Defective Control Module: A faulty control module responsible for regulating the Reductant Heater 1 Control Circuit can also cause high voltage issues.
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 09, 2024
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Code P20BC GMC Description

The P20BC diagnostic trouble code for GMC vehicles specifically refers to an issue with the Reductant Heater 1 Control Circuit registering high voltage. This code is related to the Selective Catalytic Reduction (SCR) system, which is responsible for reducing harmful emissions in the vehicle's exhaust gases. The Reductant Heater 1 Control Circuit is a crucial component of the SCR system that helps to heat the diesel exhaust fluid (DEF) to optimize its efficiency in reducing nitrogen oxide emissions.

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

Common Causes of P20BC GMC

  1. Faulty Reductant Heater Element: The most common cause of the P20BC code is a malfunctioning heater element within the Reductant Heater.
  2. Wiring Issues: Corrosion, damage, or loose connections in the wiring harness associated with the Reductant Heater can trigger this code.
  3. Defective Control Module: A faulty control module responsible for regulating the Reductant Heater 1 Control Circuit can also cause high voltage issues.
  4. Software Malfunction: Sometimes, the PCM may register false high voltage readings due to a software glitch or calibration error.

Symptoms of P20BC GMC

  1. Check Engine Light: The most common symptom associated with the P20BC code is the illumination of the Check Engine Light on the vehicle's dashboard.
  2. Reduced Fuel Efficiency: A malfunctioning Reductant Heater can impact the efficiency of the SCR system, leading to decreased fuel economy.
  3. Poor Performance: The vehicle may experience a decrease in overall performance, including reduced acceleration and power.
  4. Failed Emissions Test: If the issue is not resolved, it may cause the vehicle to fail emissions tests due to increased nitrogen oxide emissions.

How to Fix P20BC GMC

  1. Diagnose the Issue: Use a diagnostic scanner to read the code and pinpoint the exact cause of the high voltage in the Reductant Heater 1 Control Circuit.
  2. Inspect Wiring and Connections: Check the wiring harness and connections for any signs of damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test Reductant Heater Element: Test the heater element to ensure it is functioning correctly. Replace if faulty.
  4. Check Control Module: Inspect the control module for any defects or malfunctions. Replace if necessary.
  5. Clear Codes and Test Drive: After completing the repairs, clear the codes from the PCM and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P20BC GMC

The cost of repairing the P20BC code for a GMC vehicle can vary depending on the exact cause of the issue and the extent of the repairs needed. On average, the cost of parts for this repair can range from $200 to $500, with labor costs adding an additional $100 to $300. This brings the total estimated cost to approximately $300 to $800. However, it's important to note that labor rates and part prices can vary significantly based on factors such as location, vehicle make and model, and the specific repair shop. It's advisable to contact local auto repair shops for accurate pricing information.

Tech Notes for P20BC GMC

















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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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