Deutz-Fahr M56 – Engine ECU (DEUTZ EMR): Coolant Temperature Sensor: Sensor defective or signal lost

The engine control unit is receiving an implausible signal, no signal, or a voltage outside the normal operating range from the Engine Coolant Temperature (ECT) sensor. This prevents the engine from accurately monitoring its operating temperature, which can lead to poor performance, incorrect fuel injection timing, or the engine going into a protective derate mode.

• Agrotron series
• Series 5D
• 8280 Warrior
• Agroplus
• Agrofarm
• 5650 H
• 5660 HTS
• 5670 H
• 5680 H
• 5690 HTS

1. 1

   Inspect the wiring harness between the coolant temperature sensor and the EMR ECU for short circuits, chafed wires, or a cable break. Ensure the sensor connector is securely plugged in and free of corrosion or moisture.

2. 2

   Using a multimeter, measure the resistance of the sensor across its pins and compare to OEM specifications for the current ambient temperature (an open circuit or dead short indicates a failed sensor).

3. 3

   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 M56 error remains active.

4. 4

   Verify that the engine coolant is at the proper level, as an air pocket around the sensor can cause erratic readings.

1. 1

   Turn off the engine and allow it to cool completely.

   Opening a hot cooling system can cause severe burns.

2. 2

   Locate the coolant temperature sensor.

   Typically located on the engine block near the thermostat housing or cylinder head.

3. 3

   Place a drain pan directly under the sensor location.

   To catch any coolant that escapes during removal.

4. 4

   Unplug the electrical connector from the sensor.

5. 5

   Use a deep socket or wrench to carefully unscrew the defective sensor from the engine block.

6. 6

   Thread the new OEM sensor into place.

   If the sensor does not have a pre-applied thread sealant or a crush washer, apply a suitable liquid thread sealant. Torque to the manufacturer's specification.

7. 7

   Plug the electrical harness back into the new sensor.

8. 8

   Top off the engine coolant reservoir.

   To replace any fluid lost during the swap.

9. 9

   Start the engine and check for leaks.

   Use a diagnostic scan tool (such as Deutz SerDia or Jaltest) to clear the M56 fault code from the EMR ECU and verify the sensor is reading the correct temperature.