Case IH 19012 (DTC E9DE) - ECU – Engine Control Unit (ECU) / Engine Control Module (ECM): NH3 sensor open in heater circuit causing underheating.

The NH3 (Ammonia) sensor relies on an internal heating element to reach a specific operating temperature. This code triggers when the system detects an open circuit (infinite resistance) on the heater line, meaning the sensor is under-heated and cannot function properly.

• MAXXUM T4E
• 240 Series (7240, 8240, 9240)
• 5130
• Magnum
• Steiger
• Maxxum
• Farmall
• 580N Backhoes

1. 1

   Visual Inspection: Inspect the wiring harness and connectors between the NH3 sensor and the ECU. Look for melted wires, chafing against the hot exhaust, corrosion, or backed-out pins.

2. 2

   Resistance Test: Disconnect the NH3 sensor and use a multimeter to check the resistance across the sensor's internal heater pins. An open circuit (infinite resistance) confirms the sensor's internal heater has failed.

3. 3

   Voltage Test: Turn the key to the ON position and check the harness side of the connector to ensure the ECU is delivering the proper supply voltage to the heater circuit.

1. 1

   Cool Down

   Ensure the machine is turned off and the exhaust/SCR aftertreatment system has completely cooled to prevent severe burns.

2. 2

   Disconnect

   Locate the NH3 sensor on the exhaust piping (usually downstream of the SCR catalyst) and disconnect its electrical harness.

3. 3

   Remove

   Use a specialized sensor socket or wrench to carefully unscrew the defective NH3 sensor from the exhaust pipe.

4. 4

   Prep

   Apply a high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-applied from the factory). Caution: Do not get any anti-seize on the sensor probe tip, as this will contaminate it.

5. 5

   Install

   Thread the new NH3 sensor into the exhaust pipe and tighten it to the OEM specified torque.

6. 6

   Reconnect

   Plug the electrical connector back into the machine's wiring harness, ensuring the locking tab clicks into place.

7. 7

   Clear Codes

   Connect a diagnostic tool (such as the Case IH EST) to the machine, clear the 19012 (E9DE) fault code from the ECU, and run the engine to operating temperature to verify the code does not return.