Case IH 19858 – Engine Control Module (ECM) / EDC: SRC High for turbine upstream temperature sensor

The control module is receiving a voltage signal from the turbine upstream temperature sensor (EGT sensor) that exceeds the maximum allowable limit. This almost always indicates an open circuit (a broken wire, an unplugged connector, or a failed sensor with an internal break) or a short to a power source.

• Tier 4b
• Magnum
• Steiger
• Puma
• Optum
• Maxxum
• Case construction equipment

1. 1

   Visually inspect the turbine upstream temperature sensor and wiring harness on the exhaust manifold for melted, chafed, or broken wires.

2. 2

   Unplug the sensor connector and check for pushed-back pins, corrosion, or moisture inside the plug.

3. 3

   Measure the resistance across the sensor pins using a digital multimeter; an 'OL' (Open Loop) reading indicates the sensor has failed internally.

4. 4

   With the sensor unplugged and key ON, measure harness voltage to verify the presence of a 5V reference signal and a good ground. A missing 5V reference indicates a harness issue between the sensor and the ECM.

1. 1

   Cool Down

   Ensure the machine has been turned off for several hours. The exhaust manifold and turbocharger housing get extremely hot and pose a severe burn risk.

2. 2

   Disconnect Power

   Disconnect the negative battery terminal to prevent any electrical spikes.

3. 3

   Soak the Sensor

   Spray a high-quality penetrating oil onto the threads of the temperature sensor and let it sit.

4. 4

   Remove the Sensor

   Disconnect the electrical pigtail. Using a specialized sensor socket or a line wrench, carefully unscrew the sensor from the exhaust manifold.

5. 5

   Prepare the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor. Caution: Do not get any anti-seize on the sensor probe tip, as this will contaminate it and cause false readings.

6. 6

   Install

   Thread the new sensor into the manifold by hand to prevent cross-threading, then tighten it to the OEM torque specification (typically around 35 ft-lbs / 47 Nm for FPT exhaust sensors).

7. 7

   Reconnect

   Plug the electrical connector back in, ensuring the locking tab clicks into place. Secure the wire away from direct contact with the hot exhaust housing.

8. 8

   Clear Codes

   Reconnect the battery, turn the key on, and use the Case IH Electronic Service Tool (EST) or a compatible heavy-duty scan tool to clear code 19858. Start the engine and verify that the upstream turbine temperature reads normally in the live data.