Case IH 3797 – Engine Control Unit (ECU) / EDC: Diesel Particulate filter Pressure sensor : SRC High for PFlt differential pressure sensor

The signal voltage from the DPF differential pressure sensor has exceeded the maximum expected threshold (Signal Range Check - High). This typically indicates an electrical issue such as a short to voltage or a failed internal sensor circuit, though blocked or detached sensor hoses can also cause implausible pressure readings.

• Farmall
• skid steer
• Farmall 105C
• Farmall 115U
• Steiger
• MX/TG series
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)

1. 1

   Visual Hose Inspection: Check the two hose lines connecting the DPF to the differential pressure sensor. Look for detached, melted, or blocked hoses, which can cause an implausible pressure drop.

2. 2

   Wiring and Circuit Check: Inspect the sensor's wiring harness for a short circuit to power (which triggers the SRC High condition). Verify the 5-volt reference, ground, and signal return lines at the sensor connector.

3. 3

   DPF Soot Load Verification: Ensure the DPF itself is not severely overloaded with ash or soot, though a purely electrical circuit code usually points directly to the sensor or wiring.

1. 1

   Cool Down

   Ensure the engine is off and the exhaust system/DPF has completely cooled down, as these components operate at extremely high temperatures.

2. 2

   Locate the Sensor

   Locate the DPF differential pressure sensor, which is typically mounted on or near the DPF assembly.

3. 3

   Disconnect Electricals

   Unplug the 3-pin electrical connector from the sensor.

4. 4

   Remove Hoses

   Carefully release the clamps and disconnect the upstream and downstream pressure hoses from the sensor.

5. 5

   Remove Sensor

   Unbolt the sensor from its mounting bracket.

6. 6

   Clear Lines

   Blow compressed air through the disconnected hoses (away from the sensor, toward the exhaust) to ensure they are free of soot buildup or condensation blockages.

7. 7

   Install New Sensor

   Mount the new differential pressure sensor and secure the bolts.

8. 8

   Reconnect

   Reattach the pressure hoses to their respective ports and secure the clamps. Plug the electrical connector back in.

9. 9

   Clear Codes and Calibrate

   Use a diagnostic scan tool to clear fault code 3797. You may need to perform a software reset to tell the ECU that a new DPF sensor has been installed so it can recalibrate its baseline pressure readings.