Case IH 428 – ENGINE (ECM) Controller: Water in Fuel Sensor Circuit - Voltage Above Normal or Shorted to High Source

The ECM detects a voltage on the signal wire that is higher than the normal operating range. This typically means there is an open circuit, a disconnected sensor, a broken wire in the harness, or an internally failed sensor.

• MX Magnum
• STX Steiger
• TG Series
• Steiger
• Puma
• Maxxum
• MXM Series
• MXU Series
• JXU Series
• T6
• T7
• T6000
• T7000
• TSA Series
• L225

1. 1

   Visually inspect the WIF sensor connector and engine wiring harness for corrosion, pushed-back pins, or broken wires.

2. 2

   Disconnect the WIF sensor, turn the ignition key to the ON position, and measure the voltage at the harness connector (ECM side) to verify the presence of a 5-volt reference signal.

3. 3

   Perform a jumper test for circuit isolation: with the sensor disconnected, install a jumper wire between the signal and return pins on the harness connector. If the code changes to 429, the sensor is faulty. If it remains 428, there is an open circuit in the wiring harness or the ECM has failed.

1. 1

   Turn off engine

   Turn off the engine and remove the key from the ignition.

2. 2

   Place catch pan

   Place a catch pan underneath the fuel filter/water separator to catch any spilled diesel fuel.

3. 3

   Disconnect sensor

   Disconnect the electrical connector from the WIF sensor at the bottom of the filter housing.

4. 4

   Drain fuel

   Open the drain valve on the filter housing to drain the fuel into the catch pan.

5. 5

   Remove old sensor

   Carefully unscrew the old WIF sensor from the bottom of the fuel filter.

6. 6

   Inspect threads

   Inspect the threads on the fuel filter housing to ensure they are not cracked or damaged.

7. 7

   Lubricate O-ring

   Lubricate the O-ring on the new WIF sensor with clean diesel fuel.

8. 8

   Install new sensor

   Thread the new sensor into the bottom of the fuel filter. Hand-tighten only. Overtightening can crack the plastic sensor body or the filter housing.

9. 9

   Reconnect harness

   Reconnect the electrical harness to the new sensor.

10. 10

    Prime fuel system

    Prime the fuel system (using the manual primer pump if equipped) to remove air from the filter.

11. 11

    Verify and clear code

    Turn the ignition ON and verify that Fault Code 428 is now inactive. Clear the code from the ECM history using a diagnostic tool.