Case IH 19857 – Engine Control Unit (ECU): Physical Range Check low for turbine upstream temperature sensor

The control module is receiving a voltage or resistance signal from the Exhaust Gas Temperature (EGT) sensor located just before the turbocharger (upstream) that falls below the minimum acceptable physical threshold. This typically indicates an open circuit, a short to ground in the sensor's wiring harness, or a completely failed sensor probe.

• Tier 4b
• Farmall series (100C, 105A, 105C, 105U, 110A, 110C, 110U, 115A, 115C, 115U, 120U)
• Maxxum series (120, 125, 130, 140)
• Puma series (140)
• Magnum series
• Steiger series
• Axial-Flow series (5130, 5140, 7130, 7140, 7150, 7230, 7240, 7250, 9230)
• N-Series Loaders
• TLBs

1. 1

   Inspect the wiring harness leading to the turbine upstream temperature sensor for heat damage, melting, or chafing.

2. 2

   Disconnect the sensor and check the 2-pin connector for soot intrusion, corrosion, or bent pins.

3. 3

   Use a multimeter to check for a short to ground or an open circuit on the signal wire between the sensor connector and the Engine ECU harness.

4. 4

   Measure the resistance across the sensor's two pins. If the multimeter reads 'OL' (open loop/infinite resistance) or zero resistance (internal short), the sensor has failed and must be replaced.

1. 1

   Safety First

   Ensure the machine is parked on a level surface with the engine off. Allow the exhaust system and turbocharger to cool completely. The turbine upstream sensor operates in an extremely high-heat environment and can cause severe burns.

2. 2

   Disconnect Power

   Disconnect the negative battery cable to prevent electrical spikes during the repair.

3. 3

   Locate the Sensor

   Locate the turbine upstream temperature sensor. It is threaded directly into the exhaust manifold or the turbine inlet housing of the turbocharger.

4. 4

   Disconnect the Sensor

   Unplug the 2-pin electrical connector linking the sensor to the engine wiring harness.

5. 5

   Remove the Sensor

   Using a suitable wrench or specialized sensor socket (often 17mm for the M14x1.5 thread), carefully unscrew the sensor. Tip: If the sensor is seized due to heat cycling, apply penetrating oil to the threads and allow it to soak before applying torque to prevent stripping the exhaust housing threads.

6. 6

   Prepare the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-applied from the factory). Do not get any anti-seize on the sensor probe itself, as this will skew the readings.

7. 7

   Install the New Sensor

   Thread the new sensor into the housing by hand to prevent cross-threading, then tighten it to the OEM torque specification.

8. 8

   Reconnect

   Plug the electrical connector back into the engine harness and reconnect the negative battery cable.

9. 9

   Clear Codes

   Connect a diagnostic scan tool (such as the CNH Electronic Service Tool) to the machine, clear the 19857 fault code from the Engine ECU, and start the engine. Monitor the live exhaust gas temperature data to verify the new sensor is reading correctly.