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P code powertrain High severity

P1404 IAT - B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance

The OBD2 code P1404 indicates a malfunction in the Intake Air Temperature (IAT) sensor circuit related to the Exhaust Gas Recirculation (EGR) system, specifically when the EGR is in the closed position and not...

Definition

The OBD2 code P1404 indicates a malfunction in the Intake Air Temperature (IAT) sensor circuit related to the Exhaust Gas Recirculation (EGR) system, specifically when the EGR is in the closed position and not performing as expected

Common causes

  • Faulty EGR valve
  • EGR valve position sensor malfunction
  • Wiring issues or damaged connectors
  • Vacuum leaks
  • Clogged EGR passages
  • Faulty IAT sensor
  • Engine control module (ECM) issues
  • Improperly installed or damaged intake manifold gasket

Common misdiagnoses

  • Faulty EGR valve
  • Vacuum leaks
  • Faulty IAT sensor
  • Wiring issues or shorts in the circuit
  • Faulty engine control module (ECM)
  • Clogged EGR passages
  • Faulty intake air temperature (IAT) sensor circuit
  • Incorrectly installed or damaged intake manifold gasket

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 for the issue

  2. 2. Inspect the EGR System

    EGR Valve: Check the EGR valve for proper operation. Ensure it is not stuck open or closed. Clean or replace it if necessary

  3. 3. EGR Position Sensor

    If equipped, check the EGR position sensor for proper function. Test its voltage and resistance according to the manufacturer's specifications

  4. 4. Examine the IAT Sensor

    Wiring and Connectors: Inspect the wiring and connectors for the IAT sensor for any signs of damage, corrosion, or loose connections

  5. 5. Sensor Functionality

    Test the IAT sensor using a multimeter to ensure it is providing the correct voltage readings. Compare the readings to the specifications in the vehicle's service manual

  6. 6. Check for Vacuum Leaks

    Inspect the intake manifold and vacuum lines for any leaks that could affect the EGR system's performance

  7. 7. Inspect the Exhaust System

    Check for any blockages or restrictions in the exhaust system that could affect the EGR operation

  8. 8. Test the Engine Control Module (ECM)

    Ensure that the ECM is functioning correctly. If other components are working properly, the ECM may be at fault

  9. 9. 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

  10. 10. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the P1404 code for your specific vehicle make and model. Manufacturers may have known issues and recommended fixes

  11. 11. Professional Diagnosis

    If the issue persists after performing the above steps, consider seeking help from a professional mechanic who can perform more advanced diagnostics.Additional Tips: - Always refer to the vehicle's service manual for specific testing procedures and specifications. - Ensure that you are working in a safe environment and take necessary precautions when working on the vehicle. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P1404 code