Massey Ferguson 157.17 – Engine ECU (AGCO SISU POWER EEM4): Fuel Rail Pressure Not Dropping (ECU)

The engine control system has detected that the actual fuel rail pressure is not dropping as commanded, or there is a negative deviation in the rail pressure controller. This means the actual pressure in the common rail is higher than the ECU's target setpoint and the system cannot reduce it. This condition typically triggers a Level 3 power degradation (50% max power + speed limit to 1500 RPM) to protect the engine.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 6612
• 6613
• 6614
• 6615
• 6616
• 7615
• 7624
• 7715
• 7720
• 8650
• 8680
• 8727
• 8737

1. 1

   Check for Related Codes: Verify there are no active codes for the 5V reference supply or fuel pressure sensor voltage (e.g., SPN 157 FMI 3 or 4). If voltage codes are present, diagnose the wiring harness first.

2. 2

   Live Data Monitoring: Connect a diagnostic service tool (such as AGCO EDT) and monitor the Actual Fuel Rail Pressure versus the Commanded (Setpoint) Fuel Rail Pressure during cranking, idle, and shutdown.

3. 3

   Sensor Skew Test: Observe the rail pressure reading when the engine is completely shut off. If the sensor still reads high pressure when the system is physically depressurized, the sensor is skewed and must be replaced.

4. 4

   Inspect the MPROP: Check the Magnetic Proportional Valve (fuel metering unit) on the high-pressure fuel pump. If it is mechanically sticking, it may be over-pressurizing the rail.

5. 5

   Inspect the PRV: Check the mechanical Pressure Relief Valve on the fuel rail to ensure it is not stuck closed, preventing the rail from bleeding off excess pressure.

1. 1

   Power Down

   Turn off the ignition and wait a minimum of 60 seconds for the EEM4 ECU to complete its power-down cycle and save data.

2. 2

   Depressurize

   Safely relieve any residual fuel pressure in the high-pressure fuel system according to the service manual.

3. 3

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical shorts.

4. 4

   Remove Sensor

   Locate the fuel rail pressure sensor on the common rail. Disconnect its 3-pin electrical connector. Use a wrench to carefully unthread the sensor from the rail.

5. 5

   Install New Sensor

   Thread the new OEM sensor into the fuel rail and torque it to the manufacturer's exact specifications (over-torquing can damage the rail or sensor).

6. 6

   Reassemble

   Reconnect the 3-pin electrical connector and the negative battery cable.

7. 7

   Clear Codes & Test

   Turn the ignition on, use the diagnostic tool to clear the 00157.17 / SPN 157 FMI 17 fault code, and start the engine. Verify that actual rail pressure now tracks the commanded pressure and drops immediately upon shutdown. Check the sensor fitting for fuel leaks.