Case IH 1806 – ENGINE Control Module (Engine ECU): ISM-IDI High DPF Exhaust temperature

The Engine Control Unit (ECU) is detecting that the exhaust gas temperature exiting the Diesel Particulate Filter (DPF) is abnormally high, or the sensor itself has failed (an open circuit in the sensor or wiring often defaults to a maximum high-temperature reading).

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• Case SR/SV series
• Case TR/TV series
• Case IH tractors
• agricultural equipment

1. 1

   Check for accompanying codes: Upstream component failures (plugged DOC, over-fueling, or stuck doser valve) can cause genuinely high exhaust temperatures. Diagnose these first if present.

2. 2

   Inspect the wiring harness leading to the DPF outlet temperature sensor for melted wires, chafing, or corrosion at the connector.

3. 3

   Unplug the sensor and measure its resistance with a multimeter at the ECU connector. An 'open' reading (infinite resistance) confirms the sensor has failed internally.

4. 4

   Determine if the machine was attempting an active regeneration when the code triggered, as active temperature sensor DTCs will usually cause the ECU to abort regeneration.

1. 1

   Cool Down

   Park the machine on a level surface, turn off the engine, and allow the exhaust aftertreatment system to cool completely. DPF systems retain extreme heat for hours.

2. 2

   Locate the Sensor

   Locate the Exhaust Gas Temperature (EGT) sensor positioned at the outlet (rear) of the Diesel Particulate Filter canister.

3. 3

   Disconnect

   Unplug the electrical connector for the sensor.

4. 4

   Remove the Sensor

   Using a specialized sensor socket or a flare-nut wrench, carefully loosen and remove the sensor. Note: Exhaust sensors are prone to seizing. Apply penetrating oil to the threads and let it sit if the sensor is stuck to avoid stripping the exhaust bung.

5. 5

   Install the New Sensor

   Apply a small amount of high-temp anti-seize compound to the threads of the new sensor (if it does not come pre-applied). Thread it in by hand to prevent cross-threading, then tighten to the OEM torque specification.

6. 6

   Reconnect

   Plug the sensor's electrical connector back into the engine harness. Ensure the wire is routed away from direct contact with the hot DPF canister.

7. 7

   Clear Codes and Test

   Use a CNH Electronic Service Tool (EST) or compatible diagnostic scanner to clear the 1806 fault code. Run the machine up to operating temperature and, if necessary, initiate a forced stationary DPF regeneration to verify the sensor reads correctly and the exhaust temps remain within normal limits.