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P20BB GMC Code - Reductant Heater 1 Control Circuit Low Voltage

Quick Answer

The P20BB GMC code indicates an issue with the Reductant Heater 1 Control Circuit, specifically a low voltage problem. Common causes include Faulty reductant heater control module, Defective temperature sensor, Wiring issues or loose connections. 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 GMC indicates Reductant Heater 1 Control Circuit Low Voltage.
Common causes
Common causes include Faulty reductant heater control module, Defective temperature sensor, Wiring issues or loose connections.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P20BB GMC Description

The P20BB GMC code indicates an issue with the Reductant Heater 1 Control Circuit, specifically a low voltage problem. In modern diesel vehicles, Selective Catalytic Reduction (SCR) systems are used to reduce harmful emissions. The reductant heater is a crucial component of this system, as it heats up the diesel exhaust fluid (DEF) to ensure optimal emissions reduction. When the control circuit for the reductant heater is experiencing low voltage, it can lead to inefficient heating of the DEF, resulting in increased emissions and potentially causing the vehicle to fail emissions tests.

OBDII Code P20BB GMC - Reductant Heater 1 Control Circuit Low Voltage
P20BB GMC Code - Reductant Heater 1 Control Circuit Low Voltage

Common Causes of P20BB GMC

  1. Faulty reductant heater control module
  2. Defective temperature sensor
  3. Wiring issues or loose connections
  4. Corrosion or damage to electrical components
  5. Low battery voltage affecting the reductant heater system

Symptoms of P20BB GMC

  1. Check engine light illuminated on the dashboard
  2. Decreased fuel efficiency
  3. Poor engine performance
  4. Failed emissions tests

How to Fix P20BB GMC

  1. Begin by conducting a thorough diagnostic scan to confirm the P20BB GMC code and pinpoint the exact cause of the low voltage issue.
  2. Inspect the reductant heater control module, temperature sensor, and wiring for any visible signs of damage or corrosion.
  3. Test the battery voltage to ensure it is within the proper range for the reductant heater system to function correctly.
  4. Replace any faulty components, such as the control module or temperature sensor, and repair any damaged wiring or connections.
  5. Clear the diagnostic trouble codes, reset the check engine light, and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P20BB GMC

The cost of repairing a P20BB GMC code related to the Reductant Heater 1 Control Circuit Low Voltage can vary depending on the specific cause of the issue and the make and model of the vehicle. In general, the parts needed for this repair, such as a new control module or temperature sensor, can range from $100 to $300. Labor costs at auto repair shops typically range from $80 to $150 per hour, with the total repair cost likely falling between $200 and $500. It is advisable to consult with a qualified mechanic or dealership for a more accurate cost estimate based on your vehicle's specific needs and location.

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Tech Notes for P20BB 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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