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P0699 Auxiliary Emission Control Circuit Low

The OBD2 code P0699 indicates a low voltage condition in the auxiliary emission control circuit, which may affect the operation of emission control systems

Definition

The OBD2 code P0699 indicates a low voltage condition in the auxiliary emission control circuit, which may affect the operation of emission control systems

Common causes

  • Faulty auxiliary emission control circuit component
  • Damaged wiring or connectors in the circuit
  • Short circuit in the auxiliary emission control circuit
  • Open circuit in the auxiliary emission control circuit
  • Faulty engine control module (ECM)
  • Poor ground connection
  • Corroded connectors or terminals

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Bad wiring or connectors
  • Malfunctioning temperature sensors
  • Defective auxiliary emission control devices
  • Incorrectly diagnosed fuel system issues
  • Misinterpreted O2 sensor problems
  • Ignition system faults
  • Vacuum leaks
  • Exhaust system issues
  • 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. This can provide more context and help identify related issues

  2. 2. Inspect Wiring and Connectors

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

  3. 3. Pay special attention to the wiring harnesses leading to components like the EGR (Exhaust Gas Recirculation) valve, EVAP (Evaporative Emission Control) system, or any other related sensors

  4. 4. Test the Auxiliary Emission Control Components

    Identify the specific components related to the auxiliary emission control circuit (e.g., EGR valve, EVAP solenoid, etc.) and test them according to the manufacturer's specifications

  5. 5. Use a multimeter to check for proper voltage and resistance in the circuit

  6. 6. Check for Ground Issues

    Ensure that all ground connections related to the auxiliary emission control circuit are secure and free of corrosion. A poor ground can lead to low voltage readings

  7. 7. Inspect the Fuses

    Check the vehicle’s fuse box for any blown fuses that may be related to the auxiliary emission control system. Replace any blown fuses and retest

  8. 8. Perform a Visual Inspection of the Emission Control System

    Look for any obvious signs of leaks or damage in the emission control system components. This includes hoses, valves, and other related parts

  9. 9. Check for Vacuum Leaks

    Inspect for any vacuum leaks in the hoses connected to the emission control system. Vacuum leaks can affect the performance of components like the EGR valve

  10. 10. Clear the Codes and Test Drive

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

  11. 11. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P0699 code for your specific vehicle make and model. Manufacturers may have issued guidance on common issues and fixes

  12. 12. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who has experience with your vehicle's emissions system.Conclusion Troubleshooting OBD-II code P0699 involves a systematic approach to inspect and test various components of the auxiliary emission control circuit. Always refer to the vehicle's service manual for specific diagnostic procedures and specifications