Fendt 1.2.50 – Engine Control Unit (ECU): Y091 - Dispensing unit (fuel)

The engine control unit has detected that the fuel dispensing unit (MPROP valve) is not connected, has a broken wire, or has a short circuit to the battery or earth, or there is an internal ECU communication fault. The engine will shut down after 4 to 5 minutes or fail to start.

• 411 Vario COM III
• 412 Vario COM III
• 413 Vario COM III
• 414 Vario COM III
• 415 Vario COM III
• 712 Vario COM III
• 714 Vario COM III
• 716 Vario COM III
• 718 Vario COM III
• 818 Vario COM III
• 820 Vario COM III
• Fendt 300 Vario (COM III)
• Fendt 400 Vario (COM III) / Farmer 400
• Fendt 700 Vario (COM III) / Favorit 700
• Fendt 800 Vario (COM III, S4)
• Fendt 900 Vario (COM III, S4) / Favorit 900

1. 1

   Ensure the engine is off and the high-pressure fuel system has fully depressurized before performing any physical inspections.

2. 2

   Locate the Y091 fuel dispensing unit on the high-pressure fuel pump, typically on the right side of the engine behind the fuel filter.

3. 3

   Check the electrical connector at separation point X1662 on the Y091 unit for disconnected plugs, chafed wires, or corrosion.

4. 4

   Use a multimeter to test the wiring harness between the Y091 unit and the Engine ECU for continuity, cable breaks, or a short circuit to ground/battery.

5. 5

   Connect the SERDIA or Fendias diagnostic tool to read specific KWP/FC sub-codes (e.g., FC:00B0-00B3 for wiring faults, FC:00B6-00BC for internal ECU faults).

1. 1

   Depressurize system

   Turn off the tractor, remove the key, and wait for the high-pressure fuel system to naturally depressurize.

2. 2

   Locate fuel pump

   Access the right side of the engine and locate the high-pressure fuel pump behind the fuel filter.

3. 3

   Disconnect wiring

   Disconnect the wiring harness at the Y091 dispensing unit (connector X1662).

4. 4

   Repair wiring

   If the diagnostic checks revealed a wiring fault, repair the broken wire or short circuit in the harness.

5. 5

   Replace dispensing unit

   If the wiring tests perfectly, the Y091 dispensing unit itself has failed electrically and must be replaced.

6. 6

   Clean area

   Thoroughly clean the area around the high-pressure pump to ensure absolutely no dirt enters the fuel system.

7. 7

   Install replacement unit

   Unbolt and remove the faulty Y091 dispensing unit from the high-pressure pump and install the replacement unit.

8. 8

   Bleed fuel system

   Bleed the fuel system according to the procedures outlined in the operator's manual.

9. 9

   Clear error codes

   Connect the SERDIA or Fendias diagnostic tool and clear the error codes.

10. 10

    Verify repair

    Start the engine and verify that the 5-minute shutdown warning no longer appears and the tractor idles normally.