Fendt 5.1.9D – Engine Control Unit (EDC / Deutz engine control): B091 - Sensor, water in fuel

This fault code indicates that the water level in the fuel filter/water separator has exceeded the maximum setpoint range. Alternatively, it can be triggered by a broken wire or a short circuit in the B091 sensor's electrical circuit.

• 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
• Fendt 400 Vario
• Fendt 700 Vario
• Fendt 800 Vario
• Fendt 900 Vario

1. 1

   Check the fuel filter / water separator bowl for visible water accumulation.

2. 2

   If no water is present, inspect the wiring harness and connector leading to the B091 water-in-fuel sensor for broken wires, chafing, or short circuits.

1. 1

   Locate the Separator

   Locate the primary fuel filter and water sedimentor/separator container on the engine.

2. 2

   Drain the Water

   Open the drain valve at the bottom of the water separator bowl. Allow the fluid to drain into a suitable container until pure diesel fuel begins to flow, then close the valve securely.

3. 3

   Test the System

   Turn the ignition on to see if the fault code clears.

4. 4

   Sensor Replacement (If Necessary)

   If the code remains active after draining the water and verifying the wiring integrity, the B091 sensor itself has likely failed internally and must be replaced.

5. 5

   Clear the Code

   Use the FENDIAS diagnostic tool or SERDIA (Deutz engine diagnostic software) to clear the stored fault codes from the engine control unit.