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P code powertrain Medium severity

P0690 Auxiliary Emission Control Circuit

The OBD2 code P0690 indicates a malfunction in the auxiliary emission control circuit, which is responsible for monitoring and controlling emissions-related components in the vehicle

Definition

The OBD2 code P0690 indicates a malfunction in the auxiliary emission control circuit, which is responsible for monitoring and controlling emissions-related components in the vehicle

Common causes

  • Faulty auxiliary emission control circuit
  • Open or shorted wiring in the circuit
  • Bad connectors or terminals
  • Malfunctioning emission control components
  • Failed engine control module (ECM)
  • Poor ground connections
  • Corroded or damaged wiring harness

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Wiring issues or shorts in the circuit
  • Faulty sensors related to the emission control system
  • Bad ground connections
  • Issues with the auxiliary emission control device itself
  • Incorrectly diagnosed fuel system problems
  • Misinterpretation of other related codes
  • Battery or charging system problems

Troubleshooting steps

  1. 1. Check for Additional Codes

    Use an OBD-II scanner to check for any other trouble codes that may be present. Addressing related codes can help pinpoint the issue

  2. 2. Inspect Wiring and Connectors

    Visually inspect the wiring and connectors associated with the auxiliary emission control circuit. Look for signs of damage, corrosion, or loose connections

  3. 3. Pay special attention to any connectors that may have been disturbed during previous repairs

  4. 4. Test the Circuit

    Use a multimeter to test the voltage and ground at the relevant connectors. Ensure that the circuit is receiving the correct voltage and that the ground is solid

  5. 5. Check for continuity in the wiring to ensure there are no breaks or shorts

  6. 6. Check the Auxiliary Emission Control Components

    Identify the specific components controlled by the auxiliary emission control circuit (e.g., EGR valve, EVAP solenoid) and test them individually

  7. 7. Ensure that these components are functioning correctly and are not stuck or malfunctioning

  8. 8. Inspect the PCM (Powertrain Control Module)

    In some cases, the issue may be related to the PCM itself. Check for any software updates or recalls that may apply to your vehicle

  9. 9. If necessary, perform a reset or reprogram the PCM

  10. 10. Look for Vacuum Leaks

    If the auxiliary emission control system relies on vacuum, inspect for any vacuum leaks that could affect its operation

  11. 11. Check for Ground Issues

    Ensure that all ground connections related to the emission control system are clean and secure. Poor grounding can lead to erratic behavior

  12. 12. Perform a Visual Inspection of Related Systems

    Inspect other related systems, such as the fuel system and exhaust system, for any issues that could affect emissions

  13. 13. Clear Codes and Test Drive

    After performing repairs or adjustments, clear the trouble codes and take the vehicle for a test drive to see if the code returns

  14. 14. Consult Repair Manuals or Technical Service Bulletins (TSBs)

    Refer to the vehicle’s repair manual or check for any TSBs related to the P0690 code for specific guidance related to your vehicle make and model.1

  15. 15. Seek Professional Help

    If the issue persists after performing these steps, consider seeking help from a professional mechanic or technician who has experience with OBD-II diagnostics. By following these troubleshooting steps, you can systematically identify and resolve the issue associated with the P0690 code