Fendt 05.1.9D – A051 - ECU, Engine Control Unit (EDC 7): B091 - Sensor, water in fuel fault

The water level in the fuel filter/water separator has exceeded the maximum target range, or there is 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

   Check the fuel filter/water separator bowl to see if water has actually accumulated at the bottom.

2. 2

   Inspect the wiring harness and connector going to the B091 sensor for any visible cable breaks, chafing, or short circuits.

3. 3

   Verify that the electrode contacts inside the sensor are not fouled or corroded, which could cause a false closed circuit.

1. 1

   Drain the Water

   Locate the fuel filter/water separator assembly. Open the ventilation screw and the drain plug/valve at the bottom of the separator bowl to drain the accumulated water from the fuel tank/filter.

2. 2

   Retest

   Close the drain, prime the fuel system if necessary, and cycle the ignition. If the code was simply due to water accumulation, it should now be resolved.

3. 3

   Repair Wiring

   If the fault persists and the bowl is empty of water, repair any broken or shorted wires found during the diagnostic wiring check.

4. 4

   Replace Sensor

   If the wiring is intact and the bowl is drained but the fault remains active, the B091 sensor itself has failed internally and must be replaced.

5. 5

   Clear Codes

   Use the FENDIAS or SERDIA diagnostic software to clear the stored fault codes (FC:0057, 0059) from the A051 Engine Control Unit memory.