WOMS
P code powertrain Medium severity

P202C Reductant Tank Heater Control Circuit High

The OBD2 code P202C indicates that the control circuit for the reductant tank heater is experiencing a high voltage condition, which may suggest a malfunction in the heater or its wiring

Definition

The OBD2 code P202C indicates that the control circuit for the reductant tank heater is experiencing a high voltage condition, which may suggest a malfunction in the heater or its wiring

Common causes

  • Faulty reductant tank heater
  • Short circuit in the heater control circuit
  • Open circuit in the heater control circuit
  • Damaged wiring or connectors
  • Faulty engine control module (ECM)
  • Corroded or poor electrical connections
  • Malfunctioning temperature sensor

Common misdiagnoses

  • Faulty reductant tank heater
  • Wiring issues or shorts in the circuit
  • Defective engine control module (ECM)
  • Faulty temperature sensor
  • Issues with the reductant system or fluid quality
  • Problems with the fuel system or fuel injectors
  • Incorrectly diagnosed exhaust aftertreatment system issues

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 Tank Heater

    Visual Inspection: Check the reductant tank heater for any visible damage, corrosion, or loose connections

  3. 3. Wiring and Connectors

    Inspect the wiring harness and connectors for signs of wear, fraying, or corrosion. Ensure all connections are secure

  4. 4. Test the Reductant Tank Heater

    Resistance Test: Use a multimeter to measure the resistance of the reductant tank heater. Compare the reading to the specifications in the vehicle’s service manual. A significantly high resistance may indicate a faulty heater

  5. 5. Power Supply Test

    Check if the heater is receiving the correct voltage when the vehicle is running. If not, there may be an issue with the power supply or control circuit

  6. 6. Check the Control Circuit

    Fuses and Relays: Inspect the fuses and relays associated with the reductant tank heater circuit. Replace any blown fuses or faulty relays

  7. 7. Control Module

    If the heater and wiring are in good condition, the issue may lie with the engine control module (ECM) or the module that controls the SCR system. Check for software updates or faults in the module

  8. 8. Inspect the DEF System

    Ensure that the DEF is at the correct level and is not contaminated. Low levels or poor-quality DEF can sometimes cause issues with the SCR system

  9. 9. Clear Codes and Test Drive

    After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner. Take the vehicle for a test drive to see if the code reappears

  10. 10. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P202C code for your specific vehicle make and model. Manufacturers may have issued guidance or fixes for known issues

  11. 11. Seek Professional Help

    If the problem persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with the specific vehicle and its emissions system. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P202C code