Case IH F-4378-12 - ECU – Engine Control Unit (ECU) / Electronic Diesel Control (EDC) or Aftertreatment Control Module: NH3 sensor open or short in measuring cell circuit

The system has detected an internal open load or short circuit error specifically on the measuring cell line of the Ammonia (NH3) sensor.

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1. 1

   Check the NH3 sensor wiring between the sensor and the controller for any obvious defects, chafing, or broken lines.

2. 2

   Verify the sensor is mounted in the correct position and has not been physically damaged or dislodged.

3. 3

   If the visual inspection of the wiring and connectors is OK, verify the internal failure (open/short) within the NH3 sensor's measuring cell itself.

1. 1

   Locate the NH3 sensor

   Locate the NH3 sensor on the exhaust aftertreatment (SCR) system.

2. 2

   Remove the defective sensor

   Disconnect the wiring harness and remove the defective NH3 sensor.

3. 3

   Install the new sensor

   Install the new replacement NH3 sensor.

4. 4

   Perform a Startup counter reset

   If the machine was forced into a torque/RPM reduction mode (engine derate) due to the emissions failure, a 'Startup counter reset' must be performed using a diagnostic service tool after the new sensor is installed to restore full engine power.