Case IH 1800 – ISM-IDI: DOC Intake Temperature Sensor Out Of Range Low

The Diesel Oxidation Catalyst (DOC) Intake Temperature Sensor is sending a signal voltage that is below the minimum acceptable range, which typically points to an open circuit, a short to ground in the sensor wiring, or a complete internal failure of the sensor itself.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SV250
• SV340
• SR175
• Alpha Series

1. 1

   Visually inspect the DOC Intake Temperature Sensor and wiring harness for chafing, melting, or physical damage.

2. 2

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

3. 3

   Using a multimeter, check the signal and ground wires between the sensor connector and the ISM-IDI controller for continuity and test for a short to ground.

4. 4

   Measure the resistance across the sensor's terminals. If the multimeter reads an open circuit (infinite resistance) or a dead short, the sensor has failed internally.

1. 1

   Turn off the machine, remove the key, and disconnect the negative battery cable.

   This ensures safety and prevents electrical spikes.

2. 2

   Allow the exhaust system to cool completely.

   The DOC and surrounding exhaust components operate at extremely high temperatures.

3. 3

   Locate the DOC Intake Temperature Sensor.

   It is threaded into the exhaust pipe just upstream of the DOC muffler.

4. 4

   Carefully disconnect the electrical connector from the sensor pigtail.

5. 5

   Loosen and remove the temperature sensor from the exhaust bung.

   Use an appropriately sized wrench or crowfoot. Penetrating oil may be required if the sensor is seized from heat cycling.

6. 6

   Apply a small amount of high-temperature anti-seize to the threads of the new sensor.

   Be careful not to get any on the sensor probe itself (if not already pre-applied by the manufacturer).

7. 7

   Thread the new sensor into the exhaust bung and tighten to the OEM torque specification.

8. 8

   Reconnect the electrical connector.

   Ensure it clicks securely into place.

9. 9

   Reconnect the negative battery cable.

10. 10

    Clear the fault code and verify the repair.

    Turn the key on and use a diagnostic scan tool to clear the 1800 fault code. Start the engine and verify that the code does not return and that the sensor is reading a plausible temperature.