Fendt 1E.1.07 – Engine Control Unit (ECU): B091 - Water separator sensor

The water level in the fuel filter/water sedimentor has exceeded the maximum target range, or the system has detected a cable break or short circuit in the sensor's wiring.

• 309 Vario COM III
• 310 Vario COM III
• 311 Vario COM III
• 312 Vario COM III
• 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 400 Vario (COM III)
• Fendt 700 Vario (COM III)
• Fendt 800 Vario (COM III)
• Fendt 900 Vario (COM III)

1. 1

   Visually inspect the fuel filter/water sedimentor bowl to verify if water has actually accumulated

2. 2

   Inspect the wiring harness and connector leading to the B091 sensor for any visible signs of a cable break, chafing, or short circuit

3. 3

   Verify if the sensor's electrode contacts are contaminated with debris or damaged, which could cause a false closed circuit

1. 1

   Drain the Filter

   Locate the water sedimentor/fuel filter assembly on the engine. Open the drain plug/ventilation screw on the water separator to drain the accumulated water.

2. 2

   Purge

   Close the drain plug once pure diesel fuel begins to flow.

3. 3

   Test

   Turn on the tractor's ignition to see if the fault code clears automatically.

4. 4

   Electrical Testing

   If the filter is empty but the code remains, use a multimeter to test the B091 sensor wiring for continuity and shorts to ground/power (referencing Sheet 22 or 36 of the Deutz engine control wiring diagram). Repair any broken wires.

5. 5

   Replace Sensor

   If the wiring is intact and no water is present, the B091 sensor itself has failed and must be replaced.

6. 6

   Clear Codes

   Clear the stored fault codes using the SERDIA (Deutz) or FENDIAS diagnostic software.