New Holland ENG 3275 – Engine Control Module (ECM): Fuel Low Pressure Sensor Dynamic Plausibility Test - Below Map

During engine operation, the engine computer runs a dynamic plausibility test comparing the actual reading from the fuel low-pressure sensor (which monitors the fuel supply pressure before the high-pressure injection pump) against an expected performance map. A 'Below Map' condition means the sensor is reporting a pressure or voltage value that is lower than the minimum expected threshold for the current engine load and speed. This can indicate a failing sensor, high resistance in the sensor wiring, or a genuine low fuel supply pressure issue (such as a restriction).

• T8.xxx Series
• CR9090
• CX8080 Elevation
• CX8090 Elevation

1. 1

   Connect a mechanical fuel pressure gauge to the low-pressure fuel circuit and compare the actual physical pressure against the live data reading from the sensor to determine if the sensor is inaccurate or if the engine is starving for fuel.

2. 2

   Check the primary and secondary fuel filters for severe clogging, restrictions, or water contamination.

3. 3

   Ensure the low-pressure fuel supply pump (lift pump) is operating correctly and delivering adequate flow and pressure.

4. 4

   Inspect the fuel supply lines from the tank to the engine for kinks, collapsed hoses, or air intrusion (suction leaks).

5. 5

   Inspect the wiring harness and connector for the Fuel Low Pressure Sensor for chafing, corrosion, or loose pins. Test the 5V reference, ground, and signal return circuits for high resistance.

1. 1

   Replace fuel filters or lift pump

   If the mechanical gauge confirms that fuel supply pressure is actually low, replace the fuel filters first. If pressure remains low, diagnose and replace the failing lift pump or restricted fuel lines.

2. 2

   Replace Fuel Low Pressure Sensor

   If the mechanical gauge shows normal pressure but the sensor is reporting a low value to the ECM, disconnect the battery and replace the faulty Fuel Low Pressure Sensor.

3. 3

   Repair wiring

   If electrical testing reveals a wiring fault, repair the damaged section of the harness or splice in a new connector pigtail.

4. 4

   Prime and bleed fuel system

   After replacing any fuel system components, properly prime and bleed the fuel system to remove all trapped air.

5. 5

   Clear fault code

   Reconnect the battery, start the engine, and use the CNH EASy diagnostic tool (or equivalent) to clear the fault code.

6. 6

   Test drive

   Test drive or run the machine under load to verify that the sensor reading now stays within the expected map parameters and the code does not return.