Engine-CodesGeneric – P20BC

P20BC Code - Reductant Heater 1 Control Circuit High Voltage

Quick Answer

The diagnostic trouble code (DTC) P20BC refers to the Reductant Heater 1 Control Circuit High Voltage. Common causes include Short Circuit: A short circuit in the control circuit or wiring harness can cause the voltage to spike, triggering this code, Faulty Control Module: A malfunctioning control module that regulates the reductant heater can also lead to a high voltage condition, Wiring Harness Damage: Damage to the wiring harness that connects the control module to the reductant heater can disrupt the electrical flow and cause high voltage. 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 indicates Reductant Heater 1 Control Circuit High Voltage.
Common causes
Common causes include Short Circuit: A short circuit in the control circuit or wiring harness can cause the voltage to spike, triggering this code, Faulty Control Module: A malfunctioning control module that regulates the reductant heater can also lead to a high voltage condition, Wiring Harness Damage: Damage to the wiring harness that connects the control module to the reductant heater can disrupt the electrical flow and cause high voltage.
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 12, 2024
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Code P20BC Description

The diagnostic trouble code (DTC) P20BC refers to the Reductant Heater 1 Control Circuit High Voltage. This code indicates that there is an issue with the control circuit for the reductant heater in the vehicle's emissions system. The reductant heater is responsible for heating the diesel exhaust fluid (DEF) to help reduce emissions of nitrogen oxides (NOx) in diesel engines. When the reductant heater control circuit detects a high voltage, it means that there is an electrical problem that is preventing the heater from functioning properly.

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

Common Causes of P20BC

  1. Short Circuit: A short circuit in the control circuit or wiring harness can cause the voltage to spike, triggering this code.
  2. Faulty Control Module: A malfunctioning control module that regulates the reductant heater can also lead to a high voltage condition.
  3. Wiring Harness Damage: Damage to the wiring harness that connects the control module to the reductant heater can disrupt the electrical flow and cause high voltage.
  4. Defective Reductant Heater: A malfunctioning reductant heater itself can cause the control circuit to detect high voltage.

Symptoms of P20BC

  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 Power: The vehicle may go into a reduced power mode to protect the engine from potential damage caused by the high voltage condition.
  3. Poor Fuel Efficiency: The vehicle may experience reduced fuel efficiency due to the inefficient operation of the emissions system.
  4. Failed Emissions Test: If the reductant heater control circuit is not functioning correctly, the vehicle may fail an emissions test due to increased NOx emissions.

How to Fix P20BC

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the trouble code and perform tests to pinpoint the exact cause of the high voltage condition.
  2. Inspect Wiring: Check the wiring harness for any signs of damage or corrosion and repair or replace as needed.
  3. Test Control Module: Test the control module to determine if it is functioning correctly and replace if necessary.
  4. Replace Reductant Heater: If the reductant heater is found to be defective, replace it with a new unit to restore proper function.

Cost to Fix P20BC

The cost of repairing a reductant heater control circuit high voltage issue can vary depending on the specific cause of the problem and the make and model of the vehicle. In general, the cost of parts for this repair can range from $200 to $500, with labor costs adding an additional $150 to $300. Overall, the total repair cost could range from $350 to $800. It is important to note that diagnostic time and labor rates at auto repair shops can vary, so it is recommended to obtain quotes from multiple shops to find the best price for the repair.

Tech Notes for P20BC

























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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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