Case IH 17638 (F-3251-14) - ECU – Engine Control Module (ECM) / Engine ECU: Differential pressure sensor: measured data invalid (secure check failed)

The engine's control system has detected an implausible signal or a failed internal security/plausibility check from the Diesel Particulate Filter (DPF) differential pressure sensor. When the data is invalid, the system cannot accurately monitor the DPF, which can prevent automatic exhaust regenerations and lead to a derated engine state.

• VESTRUM CVX
• Farmall 40
• Farmall 45
• Farmall 50
• Farmall 85A
• Farmall 95A
• Farmall 105A
• Farmall 115A
• Farmall 85C
• Farmall 95C
• Farmall 105C
• Farmall 115C
• Farmall 95U
• Farmall 105U
• Farmall 115U
• Maxxum Series
• Puma Series
• Optum Series

1. 1

   Check the DPF differential pressure sensor's electrical connector and wiring harness for corrosion, chafing, or loose pins.

2. 2

   Inspect the pressure differential tubes/hoses that connect the sensor to the DPF. Look for cracks, melting, leaks, or blockages caused by soot, ash, or condensation buildup.

3. 3

   Use a diagnostic scan tool to monitor the live data from the differential pressure sensor. Check if the pressure reading changes logically with engine RPM or if it remains static/erratic.

4. 4

   Look for related codes (e.g., 17639 for internal failure, 17641 for over-voltage, or 17643 for under-voltage) which can help isolate whether the issue is strictly electrical or mechanical.

1. 1

   Preparation

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Sensor

   Find the DPF differential pressure sensor, which is typically mounted on a bracket adjacent to the Diesel Particulate Filter (DPF) assembly.

3. 3

   Disconnect Electricals

   Unplug the electrical wiring harness connector from the sensor.

4. 4

   Remove Hoses

   Carefully loosen and disconnect the upstream and downstream pressure hoses/metal lines from the sensor. Note: Mark them if necessary to ensure they are not swapped during reinstallation.

5. 5

   Remove Sensor

   Remove the mounting bolts securing the sensor and take out the faulty unit.

6. 6

   Clear the Lines

   Inspect and clean the pressure lines. Use low-pressure compressed air to blow out the lines (blow away from the sensor end toward the exhaust) to ensure they are free of soot or condensation blockages.

7. 7

   Install New Sensor

   Mount the new differential pressure sensor and secure it with the mounting bolts.

8. 8

   Reconnect

   Reattach the pressure hoses to their correct ports and plug in the electrical wiring harness.

9. 9

   Restore Power

   Reconnect the battery.

10. 10

    Clear Codes and Test

    Connect a diagnostic scan tool to clear the 17638 fault code. Start the engine and perform a stationary (forced) DPF regeneration or a test drive under load to verify that the sensor is reading correctly and the code does not return.