Massey Ferguson 157.15 – ECU: Fuel Rail Pressure Below Requested Pressure (ECU)

The rail pressure controller is actively trying to increase the fuel pressure (positive deviation), but the actual rail pressure remains below the requested or expected normal operating range.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• 4707
• 4708
• 4709
• 4710
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Check fuel filters and low-pressure supply for restrictions. Verify the low-pressure supply pump is delivering at least 5 bars (72 psi) between the filter and high-pressure pump inlet, and check for air intrusion.

2. 2

   Test the pressure relief valve (high-pressure limit valve) on the fuel rail to ensure it is not leaking high-pressure fuel back into the return line.

3. 3

   Perform an injector leak-off (return flow) test to identify worn injectors with excessive internal leakage (e.g., more than 40-50 ml during a pressure override test).

4. 4

   Verify the fuel rail pressure sensor is functioning correctly and not sending a falsely low reading to the ECU.

1. 1

   Resolve Supply Issues

   If diagnostic checks reveal a restriction, replace the primary and secondary fuel filters and bleed the low-pressure system.

2. 2

   Replace the Pressure Relief Valve

   If the valve is bypassing fuel, relieve system pressure, remove the old valve from the fuel rail, and install the new OEM relief valve. Torque to manufacturer specifications.

3. 3

   Replace Faulty Injectors

   If the leak-off test identifies a bad injector, remove the high-pressure line and injector hold-down clamp. Extract the injector, clean the injector bore thoroughly, and install the new injector with a new copper sealing washer.

4. 4

   Replace the High-Pressure Injection Pump

   If filters, relief valve, and injectors are all functioning properly but pressure is still low, the high-pressure pump is worn out. Remove the pump (paying close attention to engine timing marks if required by the specific engine manual) and install the replacement.

5. 5

   Bleed and Test

   Prime the fuel system using the manual primer pump until all air is purged. Start the engine, check for leaks, and use a diagnostic tool to clear the 00157.15 fault code and verify that actual rail pressure now matches the requested pressure.