Case IH F-4363-00 - ECU – Engine ECU: Downstream SCR catalyst temperature sensor voltage is higher than expected.

The control module is receiving a voltage signal from the temperature sensor located after the Selective Catalytic Reduction (SCR) catalyst that exceeds the normal operating range. This typically points to an open circuit, a short to power, or a completely failed sensor (internal open).

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1. 1

   Visually inspect the downstream SCR temperature sensor wiring harness and connector for melting, chafing, or physical damage.

2. 2

   Disconnect the sensor and inspect the pins on both the sensor side and the harness side for corrosion, pushed-out pins, or moisture.

3. 3

   Check the signal wire between the sensor connector and the Engine ECU for an open circuit (continuity test) or a short to voltage.

4. 4

   Measure the resistance across the sensor's pins. If the multimeter reads 'OL' (open loop) or an extremely high resistance out of specification, the sensor has failed internally.

1. 1

   Preparation

   Turn off the machine, remove the key, and allow the exhaust system to cool completely to avoid severe burns. Disconnect the negative battery cable.

2. 2

   Locate the Sensor

   Find the downstream SCR catalyst temperature sensor on the exhaust pipe, located after the main SCR catalyst body.

3. 3

   Disconnect

   Unplug the electrical connector from the sensor harness.

4. 4

   Removal

   Using a specialized sensor socket or an open-ended wrench, carefully loosen and remove the temperature sensor from the exhaust bung. (If it is seized, penetrating oil may be required).

5. 5

   Installation

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (avoid getting any on the sensor probe itself, as this can contaminate it). Thread the new sensor into the exhaust bung by hand to prevent cross-threading.

6. 6

   Torque

   Tighten the sensor to the OEM specified torque (usually snug, but refer to the specific engine manual to avoid damaging the exhaust bung).

7. 7

   Reconnect

   Plug the electrical connector back into the machine's wiring harness, ensuring it clicks and locks into place. Secure any loose wiring with zip ties away from hot exhaust components.

8. 8

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a Case IH EST (Electronic Service Tool) or compatible diagnostic scanner to clear the F-4363-00 fault code. Start the engine and verify the code does not return.