Case IH 19019 – DCU (Dosing Control Unit): Temperature sensor before catalyst (electrical) – signal high

The control module is receiving a voltage signal from the exhaust gas temperature (EGT) sensor located before the catalytic converter (or neutralizer) that exceeds the maximum allowable threshold. A 'signal high' condition typically points to an open circuit, a disconnected sensor, a broken wire, a short to a high-voltage power source, or an internally failed sensor.

• Tier 4a
• Tier 4b
• Case IH Magnum Series
• Case IH Steiger Series
• Case IH Puma Series
• Case IH MX/TG Series

1. 1

   Locate the temperature sensor upstream of the Diesel Oxidation Catalyst (DOC) or SCR catalyst. Inspect the sensor's pigtail wiring and the main harness connector for melting, chafing, or corrosion.

2. 2

   Disconnect the sensor and check the pins for water intrusion, bent pins, or poor terminal tension.

3. 3

   Using a multimeter, check the sensor signal wire and ground wire back to the DCU for continuity. Test the signal wire for a short-to-power (which would cause the 'signal high' reading).

4. 4

   Measure the resistance across the sensor's pins. If the sensor reads completely open (infinite resistance), the sensor has failed internally and must be replaced.

1. 1

   Safety First

   Turn off the engine, remove the key, and allow the exhaust system to cool completely. Disconnect the negative battery terminal.

2. 2

   Locate the Sensor

   Find the exhaust gas temperature sensor threaded into the exhaust pipe immediately before the catalytic converter assembly.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor harness.

4. 4

   Removal

   Spray penetrating oil on the sensor threads if rust is present. Carefully use a line wrench or specialized EGT sensor socket to unthread the sensor from the exhaust pipe to avoid stripping the threads.

5. 5

   Installation

   Apply a small amount of high-temperature anti-seize to the threads of the new sensor (if not already pre-applied by the manufacturer). Thread the new sensor in by hand to prevent cross-threading, then tighten to OEM torque specifications.

6. 6

   Reconnect

   Plug the electrical connector back into the harness, ensuring it clicks and locks securely.

7. 7

   Clear Codes

   Reconnect the battery. Use a diagnostic scan tool to clear the 19019 / P0428 fault code from the DCU.

8. 8

   Verify

   Start the tractor and let it reach operating temperature to ensure the code does not return and the DCU is reading plausible temperature data.