Case IH 3605 – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): Temperature of Outer control loop - Temperature deviation above Limit

The Engine Control Unit has detected that the actual temperature of the catalyst system is deviating higher than the expected or modeled temperature threshold.

• Puma
• Magnum
• Maxxum
• Steiger
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230

1. 1

   Check for related active fault codes indicating direct circuit failures (e.g., 3602, 3586-3589) and diagnose those first.

2. 2

   Perform a plausibility check on the upstream and downstream SCR catalyst temperature sensors using a diagnostic scan tool (sensors should read ambient air temperature when the engine is completely cold).

3. 3

   Inspect the wiring harness and connectors for the catalyst temperature sensors for shorts to ground, shorts to voltage, or open circuits (e.g., voltage greater than 3.30V in the signal circuit).

4. 4

   Verify DEF/Urea quality and dosing, checking for related urea quality codes (e.g., 3609) as poor reagent quality or dosing valve issues can cause abnormal temperatures.

1. 1

   Connect a dealer-level diagnostic scan tool (such as the CNH Electronic Service Tool - EST) to the machine's diagnostic port to retrieve all active and stored ECU/EDC fault codes.

   Retrieve all active and stored ECU/EDC fault codes.

2. 2

   Address any primary sensor circuit faults (like open or short circuits) first.

   Resolve direct circuit failures before proceeding.

3. 3

   Disconnect the catalyst temperature sensor(s) and inspect the pins for corrosion, moisture, or damage.

   Check the physical condition of the sensor connections.

4. 4

   Test the sensor's resistance with a multimeter and compare it against the OEM specifications for the specific engine model.

   Verify the sensor's electrical integrity.

5. 5

   If the sensor readings are out of range, or if the live data shows erratic temperature spikes that do not match physical exhaust temperatures, replace the faulty Catalyst Temperature Sensor.

   Replace the sensor if it fails resistance testing or shows erratic live data.

6. 6

   If the sensors and wiring test good, inspect the SCR dosing valve for leaks or over-dosing, which can artificially drive up catalyst temperatures.

   Check the dosing valve if the sensors are functioning correctly.

7. 7

   After replacing the faulty component, clear the fault codes using the scan tool.

   Clear codes to reset the system.

8. 8

   Run the engine through a warm-up cycle or perform a manual SCR system test/regeneration to ensure the outer control loop temperature deviation remains within the acceptable limit.

   Verify the repair by monitoring the system during operation.