Case IH 3422 – ENGINE ECU: Fuel Filter Sensor: Voltage Below Minimum Value

This indicates that the voltage signal returning from the fuel filter sensor (which monitors for a clogged fuel filter or water in the fuel) has dropped below the minimum acceptable threshold. This is typically caused by a failed sensor, a short to ground in the wiring harness, or a severely clogged filter causing abnormal sensor readings.

• Farmall
• TR270
• TR310
• TR320
• TR340
• TV380
• SR175
• L220
• Steiger 380
• Steiger 385
• Steiger 430
• Steiger 435
• Steiger 485
• STX380
• STX430
• Farmall 65C
• Farmall 75C
• Farmall 100C
• Farmall 105U
• Farmall 115U
• 7010
• 8120
• 1150K
• 1850K
• 721D
• 845B

1. 1

   Inspect the wiring harness leading to the fuel filter sensor (located at the bottom of the primary fuel filter/water separator) for chafed wires, broken connectors, or a short circuit to ground.

2. 2

   Use a multimeter to verify the primary supply voltage reaching the sensor connector. If supply voltage is correct but return signal is low, the sensor is likely internally shorted or failed.

3. 3

   Check if the primary fuel filter is severely clogged or if the water separator bowl is full of water, which can trigger erratic sensor behavior.

1. 1

   Locate the Sensor

   Locate the primary fuel filter on the engine. The fuel filter sensor is threaded into the bottom of the filter housing or the water separator bowl.

2. 2

   Drain the Fuel

   Disconnect the wiring harness from the sensor. Open the drain valve on the water separator bowl to drain the fuel into an appropriate catch container.

3. 3

   Remove the Sensor

   Carefully unscrew the sensor from the bottom of the filter by turning it counterclockwise. Caution: On some newer Case IH filter designs, the sensor threads into a spring-loaded insert. Ensure you are unthreading the sensor itself and not just spinning the internal insert, which can break the sensor housing.

4. 4

   Install the New Sensor

   Lubricate the new O-ring/seal (usually supplied with the new sensor) with a small amount of clean diesel fuel or oil. Thread the new sensor into the filter housing and hand-tighten it. Do not overtighten.

5. 5

   Reassembly

   Reconnect the wiring harness to the sensor.

6. 6

   Prime the System

   Prime the fuel system to remove air before attempting to start the engine. Clear the fault code via the diagnostic menu or EST tool and verify that code 3422 does not return.