Case IH 3274 – Engine Controller / Engine ECU (ENG): Fuel Low Pressure Sensor Dynamic Plausibility Test - Above Map

The measured fuel pressure downstream of the main fuel filter is registering higher than the possible physical maximum for the engine's current operating point. Essentially, the sensor is reading an implausibly high pressure on the low-pressure supply side of the fuel system.

• Case IH Magnum 235 – 340 (Series 4)
• Case IH Steiger
• Case IH Puma

1. 1

   Perform a fuel pressure test using a mechanical gauge to verify actual fuel pressure (minimum 5 bar / 72 psi loaded or unloaded)

2. 2

   Check for air ingress by installing a clear test line at the inlet of the fuel injection pump to observe if air is entering the system

3. 3

   Inspect the fuel return lines back to the tank for restrictions, kinks, or blockages that could cause pressure spikes on the low-pressure side

4. 4

   Verify the Fuel Low Pressure Sensor wiring harness for shorts to power or ground, and check sensor voltage output against OEM specifications

1. 1

   Inspect fuel lines

   Inspect all low-pressure fuel lines, paying special attention to the fuel return line. Remove any kinks, clear any blockages, or replace crushed lines.

2. 2

   Inspect and replace fuel filters

   Drain the water separator and inspect the fuel filters. If the filters are heavily contaminated or have not been changed at the regular service interval, replace them.

3. 3

   Disconnect sensor wiring

   If the mechanical gauge shows normal pressure but the ECU is reading implausibly high pressure, the Fuel Low Pressure Sensor is faulty. Disconnect the wiring harness from the sensor.

4. 4

   Remove sensor

   Remove the old Fuel Low Pressure Sensor from the fuel filter housing or supply line.

5. 5

   Install new sensor

   Install the new sensor and torque to OEM specifications.

6. 6

   Reconnect wiring

   Reconnect the wiring harness.

7. 7

   Bleed fuel system

   Bleed the fuel system of any air introduced during the repair.

8. 8

   Clear codes and test

   Clear the fault codes from the Engine ECU and run the machine under load to verify the code does not return.