Case IH F-173-31 - ECU – Engine Control Unit (ECU): Engine Exhaust Gas Temperature (EGT) - Condition Exists

The exhaust gas temperature has exceeded the maximum safe operational threshold, causing the system to automatically trigger a torque limitation (engine derate) to protect the engine, turbocharger, and aftertreatment system from severe thermal damage.

• MAGNUM AFS Connect
• Farmall (100C-140A)
• Maxxum (120-150)
• Puma (130-240)
• Optum (270-300)
• Magnum
• Steiger (350-620)
• Quadtrac/Rowtrac series
• Axial-Flow 240 series
• 5130
• 5140
• 7130
• 7140
• 7150
• 7230
• 7240
• 7250
• 9230
• 9240
• 9250

1. 1

   Validate sensor data using the Case IH Electronic Service Tool (EST) to monitor live EGT readings. Implausibly high temperatures on a cold engine indicate a faulty sensor or wiring.

2. 2

   Inspect the EGT sensor wiring harness, connectors, and contact surfaces for oxidation, corrosion, or chafing.

3. 3

   Check the engine air filter condition for heavy dust or impurities, as restricted air intake can cause the engine to run rich and increase exhaust temperatures.

4. 4

   Inspect the charge air cooler (CAC) piping and turbocharger hoses for boost pressure leaks.

5. 5

   Ensure the Diesel Particulate Filter (DPF) or Selective Catalytic Reduction (SCR) catalyst is not severely clogged, creating excessive exhaust backpressure.

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground cable. Allow the exhaust system to cool completely to avoid severe burns.

2. 2

   Locate the Sensor

   Locate the EGT sensor on the exhaust manifold or immediately downstream of the turbocharger (depending on the specific engine model).

3. 3

   Disconnect

   Unplug the electrical connector from the EGT sensor harness.

4. 4

   Remove the Sensor

   Use a specialized sensor socket or a flare-nut wrench to carefully unthread the EGT sensor from the exhaust pipe. (Applying penetrating oil beforehand is highly recommended, as these sensors frequently seize due to heat cycles).

5. 5

   Install the New Sensor

   Apply a small amount of high-temp anti-seize compound to the threads of the new sensor (avoiding the probe tip). Thread it in by hand to prevent cross-threading, then torque to OEM specifications.

6. 6

   Reconnect

   Plug the electrical connector back into the engine harness and secure any retaining clips.

7. 7

   Clear Codes

   Reconnect the battery, connect the diagnostic tool, and clear the F-173-31 / SPN 173 fault codes.

8. 8

   Test Run

   Start the engine and monitor the live EGT data. Perform a test drive under load to ensure the torque limitation is lifted and temperatures remain within the normal operating range.