Massey Ferguson 157.04 – Engine Control Unit (ECU) / EEM: Fuel Rail Pressure Sensor Low Voltage

The signal voltage returning from the fuel rail pressure sensor to the controller has dropped below the minimum acceptable threshold. This condition typically indicates an electrical issue such as a short to ground in the sensor signal wire, an open circuit, a loss of the 5V reference supply, or an internally failed sensor.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614 through 7626
• 7714 through 7726S
• 4600
• 5400
• 5600
• 6400
• 6600
• 7400
• 7600
• 8400
• 8600
• 2600H
• 2604H
• 2605H
• 2606H
• 2607H
• 2635

1. 1

   Inspect the 3-pin electrical connector at the fuel rail pressure sensor for pushed-back pins, corrosion, or moisture ingress.

2. 2

   Trace the wiring harness from the sensor back to the ECU. Look for chafing, melted insulation, or pinch points that could cause the signal wire to short to ground.

3. 3

   Disconnect the sensor. Turn the ignition ON (engine off). Using a multimeter, verify that the ECU is supplying a 5V reference and a good ground to the connector.

4. 4

   If the 5V reference and ground are present, and the signal wire has continuity to the ECU without shorting to ground, the sensor itself has likely failed internally and must be replaced.

1. 1

   Preparation

   Turn off the ignition and disconnect the negative battery cable.

2. 2

   Clean the Area

   Thoroughly clean the area around the fuel rail and the sensor. The high-pressure fuel system is highly sensitive to dirt and debris; no contamination can be allowed into the open rail.

3. 3

   Disconnect

   Unplug the 3-pin electrical connector from the fuel rail pressure sensor.

4. 4

   Removal

   Using the appropriate wrench, carefully unscrew the faulty pressure sensor from the fuel rail. Have a rag ready to catch residual fuel.

5. 5

   Installation

   Thread the new OEM fuel rail pressure sensor into the rail by hand to prevent cross-threading. Torque the sensor to the exact specification outlined in your specific engine's service manual (over-tightening can damage the rail or sensor).

6. 6

   Reassembly

   Reconnect the 3-pin electrical connector, ensuring it clicks securely into place. Reconnect the battery.

7. 7

   Testing

   Turn the key to the ON position to prime the fuel system. Check for any fuel leaks around the sensor threads. Use a diagnostic scan tool to clear the 00157.04 / SPN 157 FMI 4 fault code. Start the engine and verify the code does not return.