Case IH 19752 – Engine Control Module (ECM) / Engine Control Unit (ECU): Maximum rail pressure exceeded

The Engine Control Unit (ECU) has detected that the fuel rail/system pressure is too high. The fault triggers when the rail pressure exceeds a maximum safety threshold (e.g., exceeding 2250.0 bar / 32,625 psi during operation or limp-home mode).

• Tier 4b
• Puma series (115–215)
• Maxxum series (110–140)
• Farmall series (90C–120U)
• T7 series
• N-Series Loader Backhoes
• SR/SV/TR series skid steers and compact track loaders (SR250, SV300, TR320)

1. 1

   Verify if the fault is currently active using the CNH EST or PT-Box tool

2. 2

   Check for related faults regarding the Fuel Metering Unit's electrical connection (e.g., DTC-4155 / SPN-16725)

3. 3

   Inspect the engine harness, connectors, and pins to the fuel rail pressure sensor and fuel metering unit for corrosion, bent pins, or wire breaks

4. 4

   Inspect fuel return lines for kinks, blockages, or restrictions

5. 5

   Check the 5-Bar pressure relief valve on the fuel rail to ensure it is not clogged or mechanically failed

1. 1

   Resolve Wiring Issues

   If any damage was found during the wiring inspection, repair or replace the affected harness/connectors.

2. 2

   Clear Return Lines

   If the fuel return lines are restricted, clear the blockage or replace the damaged lines.

3. 3

   Replace the Fuel Metering Unit (M-Prop)

   If the wiring and return lines are intact, the fuel metering unit (located on the high-pressure fuel pump) is likely mechanically stuck open or electrically faulty. Remove and replace the metering unit.

4. 4

   Replace the Fuel Rail Pressure Sensor

   If the metering unit is functioning properly but the ECU is still reading an artificially high pressure, the fuel rail pressure sensor has likely failed and is sending skewed data. Replace the sensor.

5. 5

   Clear Codes and Test

   After replacing the faulty component, use the diagnostic tool to clear the fault codes. Run the machine and monitor the live fuel rail pressure data to confirm the repair.