Case IH 3836 – Engine Control Unit (ECU) / EDC: OxiCat downstream temperature sensor : SRC High

Signal Range Check High. The voltage signal returning from the sensor to the controller is above the maximum expected threshold, indicating an open circuit (such as a broken wire or disconnected plug) or a short to a high-voltage source.

• Farmall (100C-140A)
• Maxxum (120-150)
• Puma (130-240)
• Optum (270, 300)
• Steiger (350-620)
• Quadtrac/Rowtrac (370-620)
• Axial-Flow 5130
• Axial-Flow 5140
• Axial-Flow 7130
• Axial-Flow 7140
• Axial-Flow 7240
• Axial-Flow 9230
• Axial-Flow 9240
• Axial-Flow 9250

1. 1

   Locate the downstream temperature sensor on the exhaust aftertreatment assembly (just after the DOC). Check the sensor's electrical connector to ensure it is securely plugged in and not melted by exhaust heat.

2. 2

   Trace the wiring harness from the sensor back to the EDC. Look for chafing, broken wires, or areas where the harness may have melted against the exhaust, causing an open circuit or a short to power.

3. 3

   Disconnect the sensor and inspect the pins inside the connector for corrosion, moisture, or bent terminals.

4. 4

   Use a multimeter to measure the resistance across the sensor's terminals. If the sensor reads as an open circuit (infinite resistance/OL), the sensor has failed internally and must be replaced.

1. 1

   Safety First

   Turn off the machine, remove the key, and allow the exhaust system to cool completely. The DOC/DPF assembly operates at extremely high temperatures.

2. 2

   Disconnect

   Unplug the electrical connector from the faulty OxiCat downstream temperature sensor.

3. 3

   Removal

   Using an appropriate wrench, carefully unscrew the sensor from the exhaust pipe. Tip: If the sensor is seized due to heat cycling, apply a penetrating fluid and allow it to soak before attempting to break it loose to avoid stripping the exhaust bung threads.

4. 4

   Installation

   Thread the new Exhaust Gas Temperature Sensor (EGTS) into the exhaust bung by hand to prevent cross-threading. Tighten it to the OEM specified torque (CNH FPT exhaust sensors are typically torqued to 40.5 - 49.5 Nm / 30 - 36 lb-ft).

5. 5

   Reconnect

   Plug the sensor's electrical connector back into the engine wiring harness. Ensure it clicks into place and route the wire away from direct heat sources.

6. 6

   Clear Codes

   Turn the key on and use the CNH Electronic Service Tool (EST) or a compatible diagnostic scanner to clear fault code 3836.

7. 7

   Verification

   Start the engine and monitor the exhaust temperature data on the diagnostic tool. You may need to perform a stationary regeneration or run the engine under load to verify the sensor is reading correctly and the code does not return.