Case IH 17639 (F-3251-31) - ECU – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): Differential pressure sensor: sensor reports internal failure / measured data invalid

The sensor responsible for monitoring the exhaust gas pressure difference across the Diesel Particulate Filter (DPF) is providing invalid data or has suffered an internal electronic hardware fault.

• VESTRUM CVX
• Austoft 9900
• Farmall 115C
• Farmall 120C
• Farmall 115U

1. 1

   Inspect the electrical wiring harness and connector at the DPF differential pressure sensor for damage, corrosion, short circuits to ground, or open circuits.

2. 2

   Verify that the battery voltage is sufficient (at least 10 VDC), as low voltage can cause erratic sensor readings.

3. 3

   Inspect the two pressure pipes/hoses connecting the sensor to the DPF (upstream and downstream) for blockages, soot buildup, melting, cracks, or loose connections.

4. 4

   If the wiring is intact, voltage is good, and the hoses are clear, conclude that the sensor has an internal failure and must be replaced.

1. 1

   Turn off engine

   Turn off the engine and ensure the exhaust system and DPF have cooled down completely to avoid severe burns.

2. 2

   Locate sensor

   Find the DPF differential pressure sensor, which is typically mounted on a bracket near the exhaust/DPF assembly.

3. 3

   Disconnect electricals

   Unplug the electrical wiring harness connector from the sensor.

4. 4

   Disconnect hoses

   Carefully disconnect the two pressure hoses from the sensor. Note their orientation (one goes to the intake/upstream of the DPF, the other to the downstream/middle part of the filter) so they are not reversed during reassembly.

5. 5

   Remove sensor

   Unbolt and remove the faulty sensor from its mounting bracket.

6. 6

   Install new sensor

   Mount the new DPF differential pressure sensor and secure it to the bracket.

7. 7

   Reconnect hoses

   Reattach the pressure hoses to the correct ports on the new sensor. Ensure they are tight and have no leaks.

8. 8

   Reconnect electricals

   Plug the electrical wiring harness back into the sensor.

9. 9

   Clear codes

   Turn on the machine's ignition and use a diagnostic scan tool to clear the stored fault code (17639 / F-3251-31).

10. 10

    Test operation

    Run the engine and verify that the code does not return and that the DPF pressure readings are within normal parameters on the diagnostic tool.