Case IH 3275 – Engine Controller (ENG / ECM / EDC): Fuel Low Pressure Sensor Dynamic Plausibility Test - Below Map

The measured fuel pressure downstream of the main fuel filter has dropped below the possible physical minimum threshold for the engine's current operating point. Essentially, the engine is not receiving adequate low-pressure fuel supply, or the sensor is reading incorrectly.

• Case IH Magnum 235 - 340 (Series 4)
• Various other Case IH and New Holland tractors utilizing the CNH EDC Tier 3 and Tier 4a engine management systems

1. 1

   Inspect fuel lines for inlet restrictions or signs of air entering the fuel system

2. 2

   Install a compound test gauge (OEM 380100056) at the inlet of the low-pressure pump to measure vacuum and positive pressure (0-30 inHg vacuum, 0-30 psi positive)

3. 3

   Check the main fuel filter and water separator for blockages, heavy contamination, or water in the fuel

4. 4

   Inspect the wiring harness connected to the Fuel Low Pressure Sensor for cable breaks, short circuits, or insufficient supply voltage from the ECM

1. 1

   Relieve Pressure & Drain

   Safely relieve any residual pressure in the fuel system. Loosen the oil/fuel filter vent cap and leave it for one minute to allow fluids in the filters to drain.

2. 2

   Replace Filters

   If the diagnostic gauge shows a restriction, remove and replace the main fuel filter and/or fuel water separator.

3. 3

   Repair Wiring

   If electrical testing reveals a fault in the harness, repair or replace the damaged wiring between the Fuel Low Pressure Sensor and the Engine ECM.

4. 4

   Replace Sensor

   If the wiring is intact and fuel pressure is physically verified to be correct but the code persists, replace the Fuel Low Pressure Sensor.

5. 5

   Clear Codes

   Reconnect all components, prime the fuel system, start the engine, and use the EASy diagnostic tool (or equivalent CNH scan tool) to clear the fault codes and verify the repair.