New Holland ENG 3176 – ENGINE ECU: Fuel Metering Unit: Set point of metering unit in overrun mode not plausible

The ECU detects that the metering unit has excessively opened to maintain the desired rail pressure during an overrun condition, indicating an unexpected loss of pressure or excessive fuel leakage in the high-pressure system.

• T5.95
• T5.105
• T5.115
• T6
• T7
• T8
• L220
• SR175
• CR9090
• CX8080
• CX8090

1. 1

   Verify if the fault code is currently active or stored in history using the Electronic Service Tool (EST)

2. 2

   Inspect the wiring harness and electrical connectors at the Fuel Metering Unit on the high-pressure pump for loose contacts, chafing, heat damage, shorts to battery/ground, or open loads

3. 3

   Check the Pressure Relief Valve (PRV) on the fuel rail for sticking open or leaking, which causes continuous loss of rail pressure

4. 4

   Verify that the rail pressure sensor is reading accurately and not sending a falsely low signal to the ECU

5. 5

   Ensure the low-pressure fuel supply is adequate by checking for clogged fuel filters or a failing lift pump

1. 1

   Clear and Retest

   Clear the fault code using the diagnostic tool. Operate the machine, specifically mimicking deceleration/overrun conditions, to see if the code returns.

2. 2

   Perform a PRV Leak-Down Test

   Disconnect the return line from the Fuel Pressure Relief Valve on the fuel rail. Crank or run the engine (depending on manual specifications) and observe if fuel leaks from the valve. If fuel is bypassing the PRV under normal operating pressures, replace the PRV.

3. 3

   Replace the Fuel Metering Unit

   If the PRV is holding pressure, the wiring is intact, and the low-pressure system is supplying adequate fuel, the Fuel Metering Unit itself is likely sticking internally or failing to respond quickly enough to ECU commands. Remove the metering unit from the high-pressure pump (usually held by 2-3 Torx screws) and install a new one.

4. 4

   ECU Reprogramming/Learning

   After replacing the metering unit or high-pressure pump, use the Electronic Service Tool to clear codes and perform any required self-learning or reset procedures for the new metering valve.