Case IH 19859 – Engine Control Unit (ECU / ECM) / EDC: SRC low for turbine upstream temperature sensor

This code indicates a Signal Range Check (SRC) Low condition. The Engine Control Unit (ECU) has detected that the voltage signal from the turbine (turbocharger) upstream temperature sensor has dropped below the minimum acceptable limit. This typically means the sensor's signal circuit is shorted to a low voltage source (ground), there is an open circuit in the wiring, or the sensor itself has failed internally.

• Tier 4b
• Case IH / New Holland Tractors (Farmall, etc.)
• STM N Series Loaders
• SR175
• SR220
• SR250
• SV250
• SV300
• TR320
• TV380
• 580N
• 580SN
• 590SN

1. 1

   Connect the CNH Electronic Service Tool (EST) to verify that fault code 19859 (or 3843) is currently active.

2. 2

   Visually inspect the turbine upstream temperature sensor, its electrical connector, and the engine wiring harness for damaged wires, chafing against hot exhaust components, bent pins, or moisture/corrosion.

3. 3

   Disconnect the sensor and use a multimeter to check the signal wire for a short to ground (voltage pulled to 0V or continuity to chassis).

4. 4

   Test the sensor's resistance to determine if an internal short is causing the low voltage reading.

5. 5

   If the sensor and wiring both test good, check the ECU pins or perform an ECU software re-initialization via the EST tool.

1. 1

   Power Down

   Turn the ignition key to the OFF position. Locate the battery quick disconnector (if equipped) and turn it to the OFF position, or manually disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the Sensor

   Locate the turbine upstream temperature sensor. It is threaded into the exhaust piping directly before the turbocharger inlet.

3. 3

   Disconnect

   Carefully unplug the electrical connector from the sensor.

4. 4

   Remove Sensor

   Using the appropriate wrench or specialized sensor socket, loosen and remove the faulty temperature sensor from the exhaust manifold/turbine housing. (Penetrating oil may be required if the sensor is seized from exhaust heat).

5. 5

   Install New Sensor

   Apply a small amount of high-temp anti-seize to the threads of the new sensor (if not pre-applied by the manufacturer) and thread it into the housing. Torque to the OEM specification.

6. 6

   Reconnect

   Plug the engine wiring harness connector back into the new sensor, ensuring the locking tab clicks into place.

7. 7

   Restore Power

   Reconnect the battery or turn the battery disconnect switch back to the ON position.

8. 8

   Clear Codes

   Turn the key ON (Engine OFF). Use the CNH EST service tool to clear the inactive fault code and verify that the code does not return upon engine startup.