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P0698 Auxiliary Emission Control Circuit Range/Performance Problem

The OBD2 code P0698 indicates a problem with the auxiliary emission control circuit, specifically that its range or performance is outside the expected parameters

Definition

The OBD2 code P0698 indicates a problem with the auxiliary emission control circuit, specifically that its range or performance is outside the expected parameters

Common causes

  • Faulty auxiliary emission control module
  • Wiring issues (shorts, opens, or corrosion)
  • Poor connections or damaged connectors
  • Malfunctioning sensors related to the auxiliary emission control system
  • Software issues or programming errors in the engine control module (ECM)
  • Vacuum leaks affecting the emission control system
  • Faulty relays or fuses related to the auxiliary emission control circuit

Common misdiagnoses

  • Faulty Engine Control Module (ECM)
  • Wiring issues or shorts in the circuit
  • Faulty sensors related to the auxiliary emission control
  • Incorrectly diagnosed fuel system problems
  • Misinterpretation of other emission-related codes
  • Issues with the vehicle's battery or charging system
  • Problems with the exhaust gas recirculation (EGR) system
  • Faulty or clogged catalytic converter
  • Vacuum leaks affecting emissions performance
  • Incorrectly diagnosed ignition system issues

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 system. Look for signs of damage, corrosion, or loose connections

  3. 3. Pay special attention to the wiring harnesses leading to the components involved in the emission control system

  4. 4. Test the Auxiliary Emission Control Components

    Identify the specific components related to the auxiliary emission control system (e.g., EGR valve, evaporative emissions canister, etc.)

  5. 5. Test these components for proper operation using a multimeter or by following manufacturer-specific diagnostic procedures

  6. 6. Check for Vacuum Leaks

    Inspect the vacuum lines and hoses connected to the emission control system for leaks or blockages. A vacuum leak can cause performance issues

  7. 7. Inspect the Engine Control Module (ECM)

    Ensure that the ECM is functioning correctly. Sometimes, a software update or reprogramming may be necessary

  8. 8. Check for any signs of damage or corrosion in the ECM connectors

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

    Look for any physical damage to components such as the catalytic converter, EGR system, or other emission-related parts

  10. 10. Ensure that all components are securely mounted and not obstructed

  11. 11. Check for Proper Grounding

    Ensure that all components have a good ground connection. Poor grounding can lead to performance issues and trigger codes

  12. 12. Clear Codes and Test Drive

    After performing inspections and repairs, clear the trouble codes using the OBD-II scanner

  13. 13. Take the vehicle for a test drive to see if the code returns. Monitor the vehicle's performance and emissions system operation

  14. 14. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the P0698 code

  15. 15. Seek Professional Help

    If the issue persists after performing the above steps, consider seeking assistance from a qualified mechanic or automotive technician who has experience with emission control systems. By following these troubleshooting steps, you can systematically identify and resolve the underlying issue causing the P0698 code