Massey Ferguson 157.17 – Engine Control Unit (ECU): Fuel Rail Pressure Not Dropping (ECU)

The Engine Control Unit (ECU) detects that the fuel rail pressure is not behaving as expected. Specifically, the pressure is either failing to drop when commanded (e.g., during shutdown) or failing to reach the minimum required threshold (typically around 10 MPa / 1450 psi) after the engine has been running for a few seconds. This indicates a malfunction in the high-pressure fuel delivery system, which can lead to poor combustion, rough idling, reduced power, or a no-start condition.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724

1. 1

   Visually inspect fuel lines and filters for any signs of restrictions, blockages, or leaks.

2. 2

   Verify that the low-pressure fuel supply is adequate and that the lift pump is operational.

3. 3

   Test the fuel rail pressure sensor for proper operation and signal voltage using a multimeter, and inspect its wiring harness and connectors for corrosion, chafing, or damage.

4. 4

   Perform a fuel pressure test with a mechanical gauge to verify the actual rail pressure against the ECU's expected values.

5. 5

   Conduct an injector return flow test to check for excessive injector leakage, which bleeds off rail pressure.

6. 6

   Evaluate the fuel pressure regulator for faults or sticking.

1. 1

   Depressurize the System

   Ensure the engine is off and the high-pressure fuel system is fully depressurized before opening any lines.

2. 2

   Address Supply Issues

   Replace restricted fuel filters and repair any damaged low-pressure fuel lines. Bleed the system of air.

3. 3

   Replace Faulty Components

   If the diagnostic tests point to a faulty sensor, remove the old fuel rail pressure sensor and install the replacement (ensure correct thread pitch and torque to OEM spec). If the pressure regulator or high-pressure pump is defective, replace the affected component. If the return flow test showed excessive leakage, replace the faulty fuel injector(s).

4. 4

   System Bleed

   Prime and bleed the fuel system to ensure no air is trapped in the lines.

5. 5

   Reset and Verify

   Use a diagnostic scan tool to clear the 000157.17 DTC and reset the ECU. Start the engine and monitor live data to ensure the fuel rail pressure reaches, maintains, and drops to the required levels without triggering the code.