Case IH 3146 (F-97-31) - ECU – Engine Control Unit (ECU): Water in fuel detected or water in fuel circuit failure

The Engine Control Unit (ECU) monitors the voltage output from the water-in-fuel switch/sensor (B-012). If the ECU receives a high voltage signal from this switch, it indicates that excess water has accumulated in the fuel supply, triggering this code to warn the operator of potential engine and injection system damage.

• VESTRUM CVX
• Farmall 95U
• Farmall 105U
• Farmall 115U
• Farmall 115U Pro
• Magnum MX210
• Magnum MX230
• Magnum MX255
• Magnum MX285
• Magnum 235-340 Series 4
• Puma series
• Maxxum 115
• Maxxum 125
• 240 Series Axial-Flow Combines
• 9900 Sugar Cane Harvesters

1. 1

   Verify that the tractor battery power supply has not been connected to an external power supply (like a jump box), as voltage irregularities can trigger false sensor readings

2. 2

   Inspect the fuel filter/water separator sediment bowl for visible water or debris

3. 3

   Inspect the wiring harness and the black connector housing at the water-in-fuel switch (B-012) for damage, corrosion, or short circuits

1. 1

   Locate the Filter

   Locate the primary fuel filter/water separator assembly on the engine.

2. 2

   Disconnect Sensor

   Unplug the electrical wire harness connector from the water-in-fuel sensor located at the bottom of the filter bowl.

3. 3

   Drain the Water

   Open the drain petcock/valve on the bottom of the filter housing. Allow the fluid to drain into a catch pan until the water is purged and clean diesel fuel begins to flow out.

4. 4

   Secure and Reconnect

   Close and retighten the drain valve securely. Plug the sensor wire harness back in.

5. 5

   Prime and Test

   Reprime the fuel system if necessary. Start the tractor and observe if the fault code and warning light clear.

6. 6

   Filter/Sensor Replacement

   If the code persists immediately after draining (and you are certain no water remains), the sensor itself has likely failed or the filter is heavily contaminated. Replace the fuel filter and the water-in-fuel sensor.

7. 7

   Tank Drain

   If you are continually getting water in the filter, you may need to drain water from the lowest point of the main fuel tank using the tank's drain plug.