Massey Ferguson 157.18 – Engine Control Unit (ECU) / EEM4: Fuel Rail Pressure Below Requested Pressure / Rail pressure below normal

The measured fuel pressure in the high-pressure common rail is below the normal operating range or the pressure commanded by the engine controller. This typically results in a derate, low power, engine misfires, or a no-start condition.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• 6400 Series
• 7400 Series
• 8400 Series
• 8600 Series
• 8700 Series
• 9520
• 9530
• 9540
• 9560
• 9690
• 9790

1. 1

   Verify there is fuel in the tank (do not trust the instrument panel gauge blindly). Check for choked or clogged fuel filters due to impurities or fuel gelling/freezing.

2. 2

   During engine running, a constant diesel fuel flow should return to the fuel tank (minimum 3 L/h). To detect a return line restriction, temporarily route the diesel fuel return line from the engine connector into a canister. If the fault code goes away, the return line to the tank is clogged.

3. 3

   Inspect the rail pressure sensor wiring, connectors, and contact surfaces for oxidation. Verify the sensor is receiving a 5V power supply from the ECU. If possible, test operation with a known-good rail pressure sensor.

4. 4

   Look for wiring/connector faults at the high-pressure pump. Check the pump's operation using the Service Tool test function.

5. 5

   For 4-valve engines, check the tightness of the injector side feed pipes.

6. 6

   If all mechanical and wiring systems are functional but the fault remains active, test the system with a replacement EEM4 controller to rule out a defective ECU.

1. 1

   Resolve Supply Restrictions

   Replace the primary and secondary fuel filters. Bleed the low-pressure fuel system to ensure no air is trapped.

2. 2

   Clear Return Lines

   If the canister test proved successful, blow out or replace the restricted fuel return line running back to the fuel tank.

3. 3

   Repair Wiring

   If the 5V reference or signal wire to the rail pressure sensor is damaged or corroded, repair the harness or replace the pigtail connector.

4. 4

   Replace Sensor

   If the wiring is intact but the sensor is reading erratically or failing to register pressure, depressurize the fuel system and replace the Fuel Rail Pressure Sensor. Torque to OEM specifications.

5. 5

   Replace High-Pressure Pump

   If the sensor is accurate but the pump is physically failing to generate the commanded pressure (and the low-pressure transfer pump is supplying adequate fuel), replace the High-Pressure Fuel Pump (Bosch CP3).

6. 6

   Re-torque Lines

   Re-torque all high-pressure injector feed lines to the specifications outlined in the engine repair manual to prevent micro-leaks.

7. 7

   Clear Codes

   Use an AGCO diagnostic service tool or compatible scanner to clear the SPN 157 FMI 18 code and test-run the machine under load.