Case IH 19486 – Engine ECU: Fault check for Model based plausibility check of sixth exhaust-gas temperature

This is a plausibility error. The Engine Control Unit (ECU) continuously calculates an expected (modeled) exhaust gas temperature based on current engine load, speed, and other parameters. It then compares this modeled temperature to the actual physical reading from the 6th Exhaust Gas Temperature (EGT) sensor located in the exhaust aftertreatment system (DPF/SCR). If the actual reading deviates significantly from the expected value, the ECU flags the data as implausible and logs code 19486.

• Tier 4b
• Maxxum
• Puma
• Farmall
• Steiger
• N-Series Tractor Loader Backhoes
• Skid Steers (SR/SV series)
• Compact Track Loaders (TR/TV series)
• Wheel Loaders

1. 1

   Check for other active codes related to upstream EGT sensors (T1, T2, T3), DPF restrictions, or DEF dosing, as these often cause downstream plausibility faults.

2. 2

   Inspect the wiring harness and connectors for the 6th EGT sensor for corrosion, melted wires, or loose connections.

3. 3

   Inspect the exhaust piping upstream of the sensor for leaks, which can cause actual exhaust temperatures to drop.

4. 4

   Remove the sensor and inspect the tip for heavy soot or crystallization build-up.

5. 5

   Test the sensor's resistance using a multimeter or oscilloscope, and compare the ambient reading against an infrared (IR) thermometer.

1. 1

   Preparation

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

2. 2

   Disconnection

   Locate the 6th EGT sensor on the aftertreatment housing (DPF/SCR unit). Disconnect the electrical pigtail connector.

3. 3

   Removal

   Use a specialized sensor socket or a line wrench to carefully unthread the EGT sensor from the exhaust bung.

4. 4

   Cleaning

   Clean the mounting boss threads on the exhaust pipe. If the threads are damaged, use a thread chaser/bung repair kit.

5. 5

   Installation

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

6. 6

   Reconnection

   Reconnect the electrical harness and secure any loose wiring with high-temp zip ties.

7. 7

   Verification

   Connect a diagnostic tool, clear the fault codes, and perform a forced DPF regeneration or a loaded test drive to ensure the exhaust reaches operating temperature and the code does not return.