Case IH 19014 (DTC EBDE) - ECU – Engine ECU (ECM): NH3 sensor open or short in trim resistor circuit

The system has detected an electrical fault—specifically an open circuit or a short circuit—within the internal trim/cutoff resistor line of the NH3 (Ammonia) sensor. This sensor monitors ammonia slip in the exhaust stream as part of the Selective Catalytic Reduction (SCR) emissions system.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum Series (235–340 Series 4)
• Steiger/Quadtrac Series (620)
• Maxxum Series (115)
• TR340 Compact Track Loaders
• 580N Backhoe Loaders

1. 1

   Inspect the wiring harness and connectors running from the NH3 sensor to the NH3 sensor controller and the main ECU for broken wires, chafing, or disconnected plugs.

2. 2

   Measure the voltage and resistance (ohms) on the NH3 sensor circuit to confirm if the short or open condition is in the machine's wiring harness or internal to the sensor itself.

3. 3

   Carefully inspect the ECU and sensor connector pins (do not force standard multimeter probes directly into the ECU connector, as pins are easily damaged).

4. 4

   Verify if the machine is in a torque/RPM reduction (derate) mode, which is standard when SCR emissions components fail.

1. 1

   Replace the Sensor

   If the wiring harness is intact and the electrical fault is isolated to the sensor's internal trim resistor, replace the defective NH3 sensor.

2. 2

   Installation

   Remove the old sensor from the exhaust pipe (located after the SCR muffler) and install the new sensor. Route and secure the wiring harness away from extreme heat sources.

3. 3

   System Reset

   Perform a 'Startup counter reset' or SCR system reset using a dealer diagnostic tool (such as the CNH Electronic Service Tool) to clear the engine derate, restore full engine power, and return the machine to normal operation mode.