Deutz-Fahr M87 – Engine ECU (EMR): Water in Fuel Sensor fault

Fault code M87 indicates a Water in Fuel Sensor fault, specifically that the voltage is below normal or the circuit is shorted to ground. The sensor operates on a 5.00V reference voltage from the Engine ECU, with a normal operating range between 2.60V and 2.91V. If the controller detects a voltage of less than 0.5V, it logs this fault. During normal operation, the sensor grounds its output line when water is detected, which can trigger this condition. The sensor also grounds the line for three seconds during startup as a self-diagnostic check.

• Agrotron M600
• Agrotron M610
• Agrotron M620
• Agrotron M640
• Agrotron M650
• Agrotron X710
• Agrotron X720
• Agrotron L710
• Agrotron L720
• Agrotron TTV 610
• Agrotron TTV 620
• Agrotron TTV 630
• Agrofarm Series

1. 1

   Drain the Pre-Filter: Check if there is actually water in the fuel system. The sensing element is located at the bottom of the pre-filter. Drain the water separator daily as a standard maintenance procedure to see if the code clears.

2. 2

   Check Sensor Voltage: Back-probe the sensor connector. You should see a 5.00V reference voltage. If the reading is < 0.5V, the circuit is shorted to ground.

3. 3

   Inspect Wiring and Connectors: Check the cabling between the Water in Fuel sensor and the EMR ECU for a short circuit, cable break, or chafing. Inspect the sensor connector for water ingress, contamination, or damage.

4. 4

   ECU Reset Test: Reset the ECU by switching the ignition off, waiting until the ECU has completely shut down, and switching the ignition back on to see if the error is still active.

1. 1

   Depower ECU

   Turn off the tractor and ensure the ignition is in the OFF position to depower the EMR ECU.

2. 2

   Locate sensor

   Locate the Water in Fuel sensor. The sensor electronics are typically mounted at the back of the filter bracket, with the sensing element threaded into the bottom of the fuel pre-filter.

3. 3

   Drain fuel/water mixture

   Place a drain pan under the fuel filter and open the petcock to drain the fuel/water mixture from the housing.

4. 4

   Disconnect harness

   Disconnect the electrical harness from the sensor.

5. 5

   Remove faulty sensor

   Unthread the faulty Water in Fuel sensor from the bottom of the filter housing.

6. 6

   Install new sensor

   Install the new sensor. Note: Ensure the new sealing ring (usually included with the sensor) is properly seated to prevent air leaks in the fuel system.

7. 7

   Reconnect harness

   Reconnect the electrical harness.

8. 8

   Prime fuel system

   Prime the fuel system if necessary, then turn the ignition on to allow the ECU to perform its 3-second self-diagnostic ground check.

9. 9

   Verify repair

   Start the engine and verify that fault code M87 has cleared from the dash/display.