Case IH 19774 – Engine Control Module (ECM / Engine ECU): Counter for the DEF/AdBlue catalyst downstream Temperature monitoring

This code indicates a plausibility error or monitoring fault with the Exhaust Gas Temperature (EGT) sensor located downstream (after) the Selective Catalytic Reduction (SCR) catalyst. It is triggered if the sensor reading drifts, shorts, or deviates from expected modeled temperatures.

• Tier 4b
• Case IH Farmall series (110A, 120A, 130A, 140A)
• Case IH Magnum
• Case IH Steiger
• Case IH Patriot Sprayers
• Case IH Combines (e.g., 8230)

1. 1

   Perform a cold start temperature comparison: Let the machine cool completely to ambient temperature, then use a diagnostic tool to read the upstream and downstream SCR temperature sensors. If the downstream sensor deviates significantly from ambient, it has drifted and requires replacement.

2. 2

   Inspect the wiring harness and electrical connector leading to the downstream temperature sensor for a short to battery positive (Battery+) or a short to ground.

3. 3

   Check for cascading OBD codes such as 19775 (OBD long time fault: SCR temperature) or 19776, which often accompany 19774 when the sensor fails.

1. 1

   Safety First

   Ensure the engine is off and the exhaust system/SCR muffler has completely cooled to prevent severe burns.

2. 2

   Locate the Sensor

   Locate the SCR muffler assembly. The downstream temperature sensor is mounted on the exhaust outlet pipe, directly after the SCR catalyst.

3. 3

   Clear Obstructions

   If equipped, remove the SCR muffler and catalyst upper heat shield to gain access to the sensor.

4. 4

   Disconnect Wiring

   Carefully unplug the electrical connector for the downstream temperature sensor from the main engine harness.

5. 5

   Remove the Sensor

   Using an appropriately sized wrench or O2/EGT sensor socket, unscrew the downstream temperature sensor from the exhaust pipe. (Note: If the sensor is seized, penetrating oil may be required).

6. 6

   Install New Sensor

   Thread the new temperature sensor into the exhaust bung and tighten to the OEM specified torque.

7. 7

   Reassembly

   Reconnect the electrical connector and reinstall the upper heat shield and any exhaust clamps that were removed.

8. 8

   Clear Codes

   Connect your diagnostic tool to the Engine ECU, clear fault code 19774, and perform a test run to verify the downstream temperature is now reading plausibly.