Case IH 3790 – Engine Control Unit (ECU) / EDC: Exhaust gas differential pressure or exhaust gas relative pressure plausibility

This code indicates a plausibility error with the Diesel Particulate Filter (DPF) differential pressure sensor. The Engine Control Unit flags this sensor as defective if the engine speed is at 0 RPM and the exhaust gas pressure reads above a defined threshold (it should read atmospheric pressure/zero when off), or if the pressure differential is below the defined threshold when the engine is running.

• skid steer
• Farmall
• Magnum
• Steiger
• Maxxum
• Axial-Flow
• TV450B

1. 1

   Perform a Key-On, Engine-Off (KOEO) test using a diagnostic tool to check the exhaust gas pressure sensor reading at 0 RPM. If it reads above the defined threshold, the sensor is out of calibration or internally shorted.

2. 2

   Visually inspect the pressure sensor tubes/hoses connecting the sensor to the exhaust manifold and DPF for blockages (soot/carbon buildup), melting, or cracks.

3. 3

   Inspect the 3-pin electrical connector and wiring harness leading to the sensor for corrosion, loose contacts, or wire chafing.

4. 4

   Check the DPF for severe restriction or clogging, which can cause abnormal pressure differentials when the engine is running.

1. 1

   Cool down exhaust system

   Turn off the machine, remove the key, and allow the exhaust system and DPF to cool completely.

2. 2

   Locate sensor

   Locate the exhaust gas differential pressure sensor, typically mounted on a bracket near the DPF or exhaust manifold.

3. 3

   Disconnect electrical connector

   Disconnect the 3-pin electrical connector from the sensor.

4. 4

   Disconnect pressure tubes

   Carefully disconnect the pressure tubes/hoses from the bottom of the sensor (note the orientation of the high and low-pressure lines).

5. 5

   Remove faulty sensor

   Unbolt and remove the faulty sensor.

6. 6

   Inspect and clean tubes

   Inspect the pressure tubes for carbon blockages. Clean them out with compressed air or replace the tubes if they are damaged or heavily restricted.

7. 7

   Install new sensor

   Mount the new pressure sensor and reconnect the pressure tubes securely.

8. 8

   Reconnect electrical harness

   Reconnect the electrical harness.

9. 9

   Clear fault code

   Connect a diagnostic service tool to the machine to clear the 3790 fault code.

10. 10

    Calibrate sensor

    If required by the specific engine's service manual, use the service tool to reset the DPF parameters or calibrate the new sensor.