WOMS
P code powertrain Medium severity

P1400 DPFE Circuit Low Input

The OBD2 code P1400 indicates a low input signal from the Differential Pressure Feedback EGR (DPFE) sensor, which monitors the pressure difference across the EGR system to ensure proper operation

Definition

The OBD2 code P1400 indicates a low input signal from the Differential Pressure Feedback EGR (DPFE) sensor, which monitors the pressure difference across the EGR system to ensure proper operation

Common causes

  • Faulty DPFE sensor
  • Damaged or corroded wiring/connectors
  • Vacuum leaks in the EGR system
  • Blocked EGR passages
  • Faulty PCM (Powertrain Control Module)

Common misdiagnoses

  • EGR valve failure
  • EGR system blockage
  • Faulty DPFE sensor
  • Vacuum leaks
  • Wiring issues or shorts
  • PCM (Powertrain Control Module) failure
  • Exhaust leaks
  • Incorrectly installed or damaged hoses

Troubleshooting steps

  1. 1. Visual Inspection

    Wiring and Connectors: Check the wiring and connectors leading to the DPFE sensor for any signs of damage, corrosion, or loose connections

  2. 2. Sensor Condition

    Inspect the DPFE sensor itself for any physical damage or signs of wear

  3. 3. Check for Other Codes

    Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues

  4. 4. Test the DPFE Sensor

    Voltage Test: With the ignition on (engine off), use a multimeter to check the voltage at the DPFE sensor connector. Compare the readings to the specifications in the vehicle's service manual

  5. 5. Resistance Test

    Measure the resistance of the DPFE sensor to ensure it is within the manufacturer's specifications

  6. 6. Inspect the EGR System

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

  7. 7. EGR Passages

    Inspect the EGR passages for blockages or carbon buildup that could affect the flow of exhaust gases

  8. 8. Check for Vacuum Leaks

    Inspect the vacuum lines connected to the EGR system for any leaks or cracks that could affect the operation of the DPFE sensor

  9. 9. Test the DPFE Circuit

    Continuity Test: Use a multimeter to check for continuity in the wiring between the DPFE sensor and the engine control module (ECM)

  10. 10. Ground Test

    Ensure that the DPFE sensor has a good ground connection

  11. 11. Replace the DPFE Sensor

    If the sensor is found to be faulty after testing, replace it with a new one. Make sure to clear the codes and test drive the vehicle to see if the code returns

  12. 12. Recheck for Codes

    After performing repairs or replacements, clear the trouble codes and monitor the vehicle to see if the P1400 code reappears

  13. 13. Professional Diagnosis

    If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic who has experience with the specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P1400 code