Engine-CodesGMC – P20BF GMC

P20BF GMC Code - Reductant Heater 2 Control Circuit Low Voltage

Quick Answer

The P20BF GMC code specifically refers to the Reductant Heater 2 Control Circuit Low Voltage. Common causes include Faulty Reductant Heater: The most common cause of the P20BF code is a malfunctioning reductant heater itself, which may need to be replaced, Wiring Issues: Damage or corrosion in the wiring harness that connects the reductant heater to the control module can result in low voltage in the circuit, Defective Control Module: A faulty control module that regulates the reductant heater's operation can also trigger this code. 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
P20BF GMC indicates Reductant Heater 2 Control Circuit Low Voltage.
Common causes
Common causes include Faulty Reductant Heater: The most common cause of the P20BF code is a malfunctioning reductant heater itself, which may need to be replaced, Wiring Issues: Damage or corrosion in the wiring harness that connects the reductant heater to the control module can result in low voltage in the circuit, Defective Control Module: A faulty control module that regulates the reductant heater's operation can also trigger this code.
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 P20BF GMC Description

The P20BF GMC code specifically refers to the Reductant Heater 2 Control Circuit Low Voltage. This code indicates that there is a problem with the control circuit for the reductant heater, which is responsible for heating the diesel exhaust fluid (DEF) in order to optimize the efficiency of the selective catalytic reduction (SCR) system. The SCR system is crucial for reducing harmful emissions in diesel vehicles by converting nitrogen oxides into nitrogen gas and water vapor.

OBDII Code P20BF GMC - Reductant Heater 2 Control Circuit Low Voltage
P20BF GMC Code - Reductant Heater 2 Control Circuit Low Voltage

Common Causes of P20BF GMC

  1. Faulty Reductant Heater: The most common cause of the P20BF code is a malfunctioning reductant heater itself, which may need to be replaced.
  2. Wiring Issues: Damage or corrosion in the wiring harness that connects the reductant heater to the control module can result in low voltage in the circuit.
  3. Defective Control Module: A faulty control module that regulates the reductant heater's operation can also trigger this code.
  4. Blown Fuse: A blown fuse in the reductant heater circuit can lead to low voltage and trigger the P20BF code.
  5. Software Malfunction: Sometimes, the issue may be related to a software glitch in the vehicle's onboard computer system that controls the reductant heater.

Symptoms of P20BF GMC

  1. Check Engine Light: The most common symptom associated with the P20BF code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Fuel Efficiency: A malfunctioning reductant heater can lead to decreased fuel efficiency as the SCR system struggles to operate efficiently.
  3. Failed Emissions Test: If the SCR system is not functioning properly due to the low voltage in the reductant heater control circuit, the vehicle may fail emissions tests.
  4. Limp Mode: In severe cases, the vehicle may go into limp mode to protect the engine from potential damage, limiting the vehicle's performance.

How to Fix P20BF GMC

  1. Diagnose the Issue: Use a diagnostic scanner to read the code and pinpoint the specific cause of the low voltage in the reductant heater control circuit.
  2. Inspect Wiring: Check the wiring harness for any damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test Control Module: Test the control module to ensure it is functioning correctly, and replace if found to be faulty.
  4. Check Fuses: Inspect the fuses related to the reductant heater circuit and replace any blown fuses.
  5. Clear Code and Test Drive: After making the necessary repairs, clear the code from the vehicle's computer system and take the vehicle for a test drive to ensure the issue has been resolved.

Cost to Fix P20BF GMC

The typical repair costs for addressing the P20BF code can vary depending on the specific cause of the issue. In general, replacing a faulty reductant heater can cost anywhere from $200 to $500, while repairing wiring issues or replacing a control module may range from $100 to $300. The overall repair cost, including parts and labor, can range from $300 to $800 or more, depending on the extent of the repairs needed.

Tech Notes for P20BF 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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