Fendt 6.1.45 – Enhanced Control Unit (ECU) / Basic Control Unit (A050) or Hydraulics / Spool Valve Control Module: Plausibility error with Hall-effect speed sensor at rear PTO clutch (B021) / Front power lift switch (S021) fault

Fault 6.1.45 indicates the PTO clutch disc package is not separating properly or the B021 sensor is sending a false signal, rendering the PTO brake non-operational. Component S021 faults indicate the external front power lift switch has failed or is stuck, preventing external operation.

• 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
• Farmer 400 Vario
• Favorit 700 and 900 Vario
• Fendt 300, 400, 700, 800, and 900 Vario (COM III)
• Fendt 900 Vario S4 series (e.g., 927, 930, 933, 936, 939)

1. 1

   For 6.1.45 (PTO Sensor): Verify if the rear PTO clutch is mechanically dragging (failing to separate) or if the issue is purely electrical.

2. 2

   For 6.1.45 (PTO Sensor): Check the wiring harness and connector at the B021 Hall-effect sensor for corrosion, damage, or a short circuit.

3. 3

   For 6.1.45 (PTO Sensor): Emergency Operation Note - If the tractor must be used before repair, the PTO can still be engaged by pressing and holding the 'Engage PTO' key inside the cab for more than 5 seconds.

4. 4

   For S021 (Front Power Lift Switch): Inspect the external S021 pushbutton (typically located on the front left of the tractor) for physical damage, dirt ingress, or sticking. A stuck button ('double actuation') is a common cause for this fault.

5. 5

   For S021 (Front Power Lift Switch): Check the wiring harness at separation point X231 (the connector for S021) for continuity and voltage.

1. 1

   Disconnect battery

   To repair the S021 Switch fault: Turn off the tractor and disconnect the battery to ensure safety while working on the electrical system.

2. 2

   Locate S021 switch

   Locate the S021 external raise switch on the front power lift assembly.

3. 3

   Clean switch area

   Clean the area around the switch to ensure debris is not causing the button to stick. If the button is physically jammed and cleaning frees it, retest the system.

4. 4

   Disconnect harness at X231

   If the switch has failed internally (signal fault), trace the wire to separation point X231 and disconnect the harness.

5. 5

   Remove faulty switch

   Remove the retaining hardware holding the S021 switch in place and remove the faulty switch.

6. 6

   Install new switch

   Install the new OEM switch, route the wiring back to X231, and reconnect the harness.

7. 7

   Test external raise function

   Reconnect the battery, perform a cold start, and test the external raise function to ensure the fault is cleared.

8. 8

   Locate B021 sensor

   To repair the 6.1.45 (B021) fault: Locate the B021 Hall-effect speed sensor at the rear PTO clutch housing.

9. 9

   Disconnect sensor harness

   Disconnect the sensor harness.

10. 10

    Replace B021 sensor

    Remove the sensor from the housing and replace it with a new OEM unit.

11. 11

    Clear fault codes

    Clear the fault codes via the FENDIAS diagnostic system or the tractor's terminal.