Case IH 3587 – Engine Control Unit (ECU) / EDC: Plausibility check of catalyst system - Temperature before Catalyst not plausible.

The engine control system continuously monitors the exhaust gas temperature (EGT) entering the Selective Catalytic Reduction (SCR) system. This code is triggered when the upstream EGT sensor (located before the catalyst) sends a temperature reading that the computer determines is 'not plausible.'

• Magnum
• Maxxum
• Puma
• Steiger
• Quadtrac
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• Patriot Sprayers
• 721F
• 821F
• 921F
• TR340

1. 1

   Cold Soak Comparison: Let the machine sit overnight. Turn the key ON (engine OFF) and look at the live data for 'Temperature Before Catalyst,' 'Temperature After Catalyst,' and 'Ambient Air Temperature.' All three should read within a few degrees of each other. If the upstream sensor is drastically different, the sensor is faulty.

2. 2

   Wiring and Connector Inspection: Inspect the wiring harness leading to the upstream EGT sensor. Look for melted wires, chafing against the exhaust, or corrosion inside the 2-pin connector.

3. 3

   Exhaust Leak Check: Inspect the exhaust piping between the turbocharger and the SCR catalyst. A severe exhaust leak can draw in cold air or vent hot gas, causing erratic temperature readings.

1. 1

   Safety First

   Ensure the machine is parked on a level surface, the engine is turned off, and the exhaust system has completely cooled down to prevent severe burns. Disconnect the battery.

2. 2

   Locate the Sensor

   Locate the Exhaust Gas Temperature sensor threaded into the exhaust pipe upstream (before) the SCR catalyst/muffler assembly.

3. 3

   Disconnect Wiring

   Unplug the 2-pin electrical connector linking the sensor to the engine harness.

4. 4

   Remove the Sensor

   Using a line wrench or deep socket, unthread the sensor from the exhaust pipe. Note: EGT sensors frequently seize in the exhaust due to heat cycles. Apply penetrating oil and allow it to soak if resistance is high to avoid stripping the exhaust bung threads.

5. 5

   Install the New Sensor

   Apply a small amount of high-temp anti-seize to the threads of the new sensor (if not pre-applied from the factory). Thread it into the exhaust bung and tighten to OEM torque specifications.

6. 6

   Reconnect

   Plug the sensor's electrical connector back into the harness, ensuring it clicks securely.

7. 7

   Clear Codes

   Reconnect the battery, turn the key ON, and use a diagnostic tool to clear the 3587 fault code. Start the engine and monitor live EGT data to verify the repair.