Case IH 19769 – Engine Control Module (ECM): SCR catalyst upstream temperature sensor plausibility min threshold

The Engine Control Module has detected an implausible reading from the temperature sensor located just before the Selective Catalytic Reduction (SCR) catalyst. The sensor is reporting a temperature that is below the minimum expected threshold for the engine's current operating conditions, pointing to a sensor that has drifted out of calibration (biased low), high resistance in the sensor circuit, or a damaged sensor probe.

• Tier 4b
• Magnum
• Steiger
• Puma
• Optum
• T7-series equivalents
• Case CE N-Series Loader Backhoes

1. 1

   Perform a cold soak comparison using a diagnostic tool to verify if the SCR upstream sensor reads the same ambient temperature as the DOC upstream and SCR downstream sensors. A significantly lower or default extreme value (e.g., -40°C) indicates a faulty sensor or circuit.

2. 2

   Inspect the wiring harness and connectors between the SCR upstream temperature sensor and the EDC17CV41 ECM (including ATS interface connections and the 96-pin vehicle-side connector) for chafed wires, melted insulation, or corroded pins.

3. 3

   Check for other related fault codes for the DOC or SCR downstream sensors, which may indicate a shared ground issue or a larger ATS harness failure.

1. 1

   Turn off ignition and disconnect battery

   Turn off the machine's ignition and disconnect the battery to prevent electrical damage.

2. 2

   Locate SCR upstream temperature sensor

   Locate the SCR upstream temperature sensor on the Exhaust Gas After-treatment System (ATS). It is threaded into the exhaust pipe between the Dosing Module / DOC and the SCR catalyst.

3. 3

   Disconnect electrical connector

   Disconnect the 2-way electrical connector for the sensor.

4. 4

   Unscrew temperature sensor

   Using a suitable wrench, carefully unscrew the temperature sensor from the exhaust pipe. (Penetrating oil may be required if the sensor is seized from extreme exhaust heat).

5. 5

   Inspect and clean mounting boss threads

   Inspect the mounting boss threads on the exhaust pipe and clean them of any soot or rust.

6. 6

   Apply anti-seize to new sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if not pre-applied by the manufacturer). Ensure no anti-seize touches the sensor probe.

7. 7

   Install new sensor

   Thread the new sensor into the exhaust pipe and tighten to the OEM torque specification.

8. 8

   Reconnect electrical connector

   Reconnect the electrical connector until it clicks securely.

9. 9

   Reconnect battery

   Reconnect the battery.

10. 10

    Clear fault code and verify repair

    Connect the diagnostic tool, clear the inactive 19769 fault code, and run the engine through a warmup cycle to verify the sensor is reading correctly and the code does not return.