Fendt 06.1.50b – REAR PTO ENHANCED CONTROL: B020 - Sensor, rear PTO speed (stub shaft)

The PTO stub shaft speed exceeds 1300 RPM, or the actual speed of the stub shaft differs by more than +/- 12% from the setpoint speed of the PTO clutch, indicating a signal fault in the Hall-effect speed sensor (B020 or B021). The tractor enters an emergency operating mode requiring the operator to press and hold the 'Engage PTO' button for at least 5 seconds to engage the PTO.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• Fendt 300 Vario (COM III)
• Fendt Farmer 400 / 400 Vario (COM III)
• Fendt Favorit 700 / 700 Vario (COM III, SCR, S4)
• Fendt Favorit 900 / 900 Vario (COM III, SCR, S4)
• Fendt 800 Vario series

1. 1

   Check the wiring harness and connectors for the B020 (stub shaft) and B021 (PTO clutch) Hall-effect sensors for a 12V supply fault, an open circuit, or a short to ground.

2. 2

   Inspect the B020 and B021 sensors for physical damage, debris buildup, or improper gap spacing.

3. 3

   Check the PTO speed selection solenoid valves (Y026, Y027, Y028) to see if they are wrongly wired, seized, or stuck in the 'OFF' position.

4. 4

   Verify there is no mechanical fault or binding in the PTO speed selector mechanism.

1. 1

   Access the Rear PTO Sensors

   Locate the B020 Hall-effect speed sensor on the rear PTO stub shaft and the B021 sensor on the PTO clutch.

2. 2

   Test the Circuit

   Using a multimeter, verify that the B020 sensor is receiving its 12V reference supply. Check the signal wire back to the ECU for continuity.

3. 3

   Replace the Sensor

   If the wiring is intact but the sensor fails to output a correct speed signal (or reads >1300 RPM erratically), remove the retaining bolt, extract the faulty B020 Hall sensor, and install the replacement.

4. 4

   Inspect/Replace Solenoids

   If the sensors test fine, inspect the Y026, Y027, and Y028 solenoid valves. If any are seized, replace the faulty valve.

5. 5

   Clear Codes and Test

   Clear the fault codes via the tractor's terminal or FENDIAS diagnostic tool. Engage the PTO normally (without holding the button for 5 seconds) to confirm the repair.