Case IH 3170 – Engine Controller (Engine ECU): ISM-IDI DPF Exhaust Temperature Higher Than 700 deg C

The exhaust gas temperature exiting the Diesel Particulate Filter (DPF) has exceeded the critical threshold of 700°C (1292°F), triggering an Amber warning indicator. This condition is typically caused by an uncontrolled exothermic reaction inside the DPF (due to excessive soot or unburned fuel) or a malfunctioning exhaust gas temperature sensor reporting falsely high values.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR175
• SV185

1. 1

   Use a diagnostic service tool to check for accompanying codes (e.g., 1802, 1803, 1806, or 3171) that might point to the root cause.

2. 2

   Visually inspect the DPF Exhaust Temperature Sensor (at the DPF outlet) and its wiring harness for melted wires, chafing, or a disconnected plug.

3. 3

   Monitor live data from the DPF OUT sensor. If it reads >700°C when the engine is cold or immediately upon startup, the sensor is shorted or faulty.

4. 4

   If the sensor reads accurately, inspect for upstream failures causing DPF overheating, such as leaking fuel injectors, a malfunctioning aftertreatment burner, or excessive oil consumption.

1. 1

   Safely Cool the Machine

   Ensure the machine has been turned off and the exhaust system has completely cooled down before beginning work, as DPF components operate at extreme temperatures.

2. 2

   Replace the Sensor (If Faulty)

   Disconnect the wiring harness from the DPF Exhaust Temperature Sensor. Use a specialized sensor socket or wrench to carefully unthread the sensor from the DPF housing (apply penetrating oil if seized). Apply a small amount of anti-seize compound to the threads of the new sensor (avoiding the probe), thread it into the DPF, torque to OEM specifications, and reconnect the wiring harness.

3. 3

   Inspect the DPF Substrate

   If the sensor was not the issue and a genuine >700°C thermal event occurred, remove the DPF and inspect the internal ceramic substrate. If the face is melted, cracked, or heavily glazed, the DPF assembly is permanently damaged and must be replaced.

4. 4

   Clear Codes and Test

   Reconnect the diagnostic service tool, clear the active and stored fault codes, and start the engine.

5. 5

   Perform a Forced Regeneration

   Initiate a stationary/forced DPF regeneration via the service tool. Monitor the live exhaust temperatures to ensure they rise appropriately but remain safely below the 700°C threshold throughout the cycle.