Case IH 3810 – Engine Control Unit (ECU) / EDC: Fuel pressure Sensor: Rail pressure raw value is intermittent

The signal coming from the high-pressure fuel rail sensor is dropping out, fluctuating erratically, or losing its connection intermittently.

• Farmall
• Steiger T4B
• Farmall 90C
• Farmall 95A
• Farmall 100C
• Farmall 105A
• Farmall 110C
• Farmall 110U
• Farmall 115A
• Farmall 120C
• Farmall 120U
• Maxxum 110
• Maxxum 115
• SR220
• SR250
• SV250
• SV300
• TR320
• TV380
• 621E
• 621F
• 621G
• 721E
• 721F
• 721G

1. 1

   Check ECU Reference Voltage: Disconnect the engine sensor harness from the ECU (often at connector X-078 or X-016, depending on the machine model).

2. 2

   Place the ignition switch in the ON position.

3. 3

   Using a multi-meter, check the voltage on the ECU engine connector across the designated sensor supply pins (e.g., pin 11 to pin 26). It should read exactly 5 Volts.

4. 4

   Inspect Wiring: If the 5V reference is present, reconnect the ECU and thoroughly inspect the wiring harness between the ECU and the fuel rail pressure sensor. Look for chafing, open circuits, or shorts to a high voltage source.

1. 1

   Verify Wiring

   Complete the diagnostic checks above to rule out a wiring harness short or open circuit.

2. 2

   Relieve Fuel Pressure

   Ensure the engine is off and the high-pressure common rail system has depressurized.

3. 3

   Remove the Sensor

   Disconnect the 3-pin electrical connector from the fuel rail pressure sensor. Unthread the faulty sensor from the fuel rail.

4. 4

   Install the New Sensor

   Thread the new OEM fuel rail pressure sensor into the rail (standard thread is often M18x1.5) and torque to the manufacturer's specifications.

5. 5

   Reconnect and Clear Codes

   Reconnect the electrical harness. Use a CNH Electronic Service Tool (EST) or EASY tool to clear the fault codes.

6. 6

   Test Run

   Run the engine and verify the code does not return. If the code persists despite a new sensor and good wiring, the ECU hardware or software may be faulty and require flashing or replacement.