Massey Ferguson 157 – Engine ECU (EEM3 or EEM4): Fuel Rail Pressure High (ECU) / Rail pressure above normal.

The engine control system has detected that the measured fuel rail pressure is higher than the critical limit (typically >1800 bar). Under normal conditions, a mechanical Pressure Relief Valve (PRV) on the fuel rail is designed to open at a critical pressure threshold (1800...2000 bar) to protect the system. If the PRV suffers a mechanical failure or the fuel rail pressure sensor provides a falsely high voltage reading, the system logs this code to prevent catastrophic fuel system damage.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4607M
• 4608
• 4609
• 4610
• 4707
• 4708
• 4709
• 4710
• 5465
• 5470
• 5475
• 5480
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5710
• 5711
• 5712
• 5713
• 6465
• 6475
• 6480
• 6485
• 6490
• 6495
• 6497
• 6499
• 6612
• 6613
• 6614
• 6615
• 6616
• 6711
• 6712
• 6713
• 7465
• 7475
• 7485
• 7490
• 7495
• 7497
• 7614 through 7626
• 7714 through 7726
• 8450
• 8460
• 8470
• 8480
• 8650
• 8660
• 8670
• 8680
• 8727
• 8730
• 8732
• 8735
• 8737
• 8740

1. 1

   Connect a diagnostic service tool (like WinEEM3/EEM4 Service Tool) and monitor the live fuel rail pressure. Compare the commanded rail pressure against the actual measured rail pressure.

2. 2

   Inspect the 3-pin connector and wiring harness at the fuel rail pressure sensor for chafing, corrosion, or shorts to power, which can cause a false "high" voltage signal.

3. 3

   Check if the mechanical Pressure Relief Valve (PRV) on the fuel rail has failed closed or is sticking.

4. 4

   Ensure there are no kinks, blockages, or restrictions in the fuel return lines back to the tank, as a blocked return can cause actual rail pressure to spike.

1. 1

   Depressurize the System

   Ensure the engine is off and the high-pressure fuel system has had adequate time to depressurize before cracking any lines.

2. 2

   Inspect/Clean Connections

   Disconnect the 3-pin connector at the fuel rail pressure sensor. Clean the contacts with electrical contact cleaner and verify the wiring integrity.

3. 3

   Replace the Sensor (If Faulty)

   If diagnostics point to a false high reading (e.g., the sensor reads high pressure even when the engine is off), unthread the old sensor (typically M14 x 1.5 or M18 x 1.5 thread) from the fuel rail. Install the new sensor and torque to OEM specifications.

4. 4

   Address the PRV/Fuel Rail

   If the sensor is accurate and the pressure is genuinely exceeding 1800 bar, the Pressure Relief Valve (PRV) or the high-pressure fuel pump metering unit (MPROP) is faulty. Replace the PRV (or the entire fuel rail assembly if the PRV is non-serviceable).

5. 5

   Clear Codes

   Reconnect all components, bleed the low-pressure fuel system if necessary, and use the diagnostic tool to clear the 00157.00 / SPN 157 FMI 0 fault code.

6. 6

   Test Run

   Start the tractor and monitor live fuel rail pressure under load to ensure it stays within the normal operating parameters.