WOMS
P code powertrain Medium severity

P20BE Reductant Heater "B" Control Circuit Performance

The OBD2 code P20BE indicates a performance issue with the control circuit for the reductant heater "B," which is part of the diesel exhaust fluid (DEF) system.

Definition

The OBD2 code P20BE indicates a performance issue with the control circuit for the reductant heater "B," which is part of the diesel exhaust fluid (DEF) system. This code suggests that the heater is not functioning properly, potentially affecting the operation of the selective catalytic reduction (SCR) system

Common causes

  • Faulty reductant heater "B"
  • Open or shorted wiring in the control circuit
  • Poor electrical connections
  • Failed control module
  • Blown fuse
  • Corroded connectors
  • Malfunctioning temperature sensor
  • Software issues in the engine control module (ECM)

Common misdiagnoses

  • Faulty reductant heater
  • Wiring issues or shorts in the control circuit
  • Defective engine control module (ECM)
  • Incorrectly diagnosed fuel system issues
  • Misinterpretation of related codes
  • Problems with the reductant tank or level sensor
  • Issues with the exhaust aftertreatment system components

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are multiple issues

  2. 2. Inspect the Reductant Heater

  3. 3. Visually inspect the reductant heater "B" for any signs of damage, corrosion, or loose connections

  4. 4. Ensure that the heater is properly mounted and that there are no physical obstructions

  5. 5. Check Electrical Connections

  6. 6. Inspect the wiring and connectors associated with the reductant heater "B" for any signs of wear, corrosion, or damage

  7. 7. Ensure that all connectors are securely attached and that there are no broken wires

  8. 8. Test the Reductant Heater

  9. 9. Use a multimeter to measure the resistance of the reductant heater. Compare the readings to the manufacturer's specifications

  10. 10. If the resistance is outside the specified range, the heater may be faulty and require replacement

  11. 11. Check the Control Circuit

  12. 12. Inspect the control circuit for the reductant heater, including any fuses or relays that may be involved

  13. 13. Test the voltage and ground at the heater connector while the vehicle is running to ensure that the control module is sending the correct signals

  14. 14. Examine the Power Supply

  15. 15. Ensure that the reductant heater is receiving the proper voltage. Check for any blown fuses or issues with the power supply circuit

  16. 16. Inspect the SCR System

  17. 17. Check the entire SCR system for any other issues that may affect the performance of the reductant heater, such as low DEF levels or contamination

  18. 18. Clear Codes and Test Drive

  19. 19. After performing repairs or replacements, clear the trouble codes using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  20. 20. Consult Technical Service Bulletins (TSBs)

  21. 21. Check for any manufacturer-specific TSBs related to the P20BE code, as there may be known issues or recommended fixes for your specific vehicle model

  22. 22. Seek Professional Help

  23. 23. If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with diesel exhaust systems and OBD-II diagnostics. By following these troubleshooting steps, you can systematically identify and resolve the issue related to the P20BE code