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P1586 Throttle Control Unit Throttle Position Malfunction

The OBD2 code P1586 indicates a malfunction in the throttle position sensor or throttle control unit, which affects the engine's throttle response and can lead to performance issues

Definition

The OBD2 code P1586 indicates a malfunction in the throttle position sensor or throttle control unit, which affects the engine's throttle response and can lead to performance issues

Common causes

  • Faulty throttle position sensor (TPS)
  • Wiring issues or damaged connectors
  • Throttle body malfunction
  • Vacuum leaks
  • Faulty engine control module (ECM)
  • Dirty or carbon-coated throttle body
  • Software issues or updates needed in the ECM
  • Electrical shorts or open circuits in the throttle control system

Common misdiagnoses

  • Faulty throttle position sensor (TPS)
  • Wiring issues or short circuits
  • Malfunctioning accelerator pedal position sensor
  • Electronic control unit (ECU) failure
  • Vacuum leaks
  • Dirty or clogged throttle body
  • Faulty mass air flow (MAF) sensor
  • Issues with the idle air control (IAC) valve
  • Fuel delivery problems
  • Ignition system faults

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 Throttle Position Sensor (TPS)

  3. 3. Check the wiring and connectors for any signs of damage, corrosion, or loose connections

  4. 4. Test the TPS using a multimeter to ensure it is functioning within the manufacturer's specifications. Look for smooth voltage changes as the throttle is opened and closed

  5. 5. Examine the Throttle Body

  6. 6. Inspect the throttle body for carbon buildup or debris that could affect its operation. Clean the throttle body if necessary

  7. 7. Ensure that the throttle plate moves freely and is not sticking

  8. 8. Check for Vacuum Leaks

    Inspect the intake manifold and vacuum hoses for any leaks that could affect the air-fuel mixture and throttle response

  9. 9. Inspect the Electronic Control Unit (ECU)

  10. 10. Ensure that the ECU is functioning properly and that there are no software issues. Sometimes, a software update may be required

  11. 11. Check for any loose or damaged wiring in the harness connecting the throttle body to the ECU

  12. 12. Perform a Throttle Position Reset

    Some vehicles require a throttle position reset after repairs. This can often be done by disconnecting the battery for a few minutes or following a specific procedure outlined in the vehicle's service manual

  13. 13. Test the Accelerator Pedal Position Sensor (APPS)

    If applicable, check the APPS for proper operation, as it works in conjunction with the TPS to control throttle position

  14. 14. Check for Other Related Components

    Depending on the vehicle, other components such as the idle air control valve (IAC) or the mass airflow sensor (MAF) may also affect throttle performance

  15. 15. Road Test the Vehicle

    After performing repairs or adjustments, take the vehicle for a test drive to see if the code returns and to ensure that the throttle response is normal