Case IH 19560 – Engine Control Module (ECM): SRC Min error for the binary lambda signal

The voltage or signal returning from the binary lambda (O2) sensor is falling below the minimum acceptable threshold programmed into the computer. This is typically caused by a short to ground, an open circuit (broken wire), or a completely failed sensor element.

• Tier 4b
• Case N-Series machines (e.g., 580N Loader Backhoes)
• Case IH tractors running FPT Tier 4B / Stage IV engines

1. 1

   Visually inspect the wiring harness leading to the Lambda sensor in the exhaust system for melted wires, chafing against the chassis, or pulled pins in the connector.

2. 2

   Disconnect the sensor and use a multimeter to check the harness side for a short to ground or an open circuit on the signal wire.

3. 3

   Verify that the sensor's internal heater circuit is receiving proper voltage (usually 12V) when the key is turned on, as a failed heater circuit can trigger signal errors.

4. 4

   Check for any exhaust leaks upstream of the lambda sensor, as fresh air entering the exhaust stream can severely skew the sensor's readings.

5. 5

   Connect the CNH Electronic Service Tool (EST) and monitor the live voltage of the Lambda sensor to determine if it is flatlined at 0V regardless of engine RPM or load.

1. 1

   Prep the Machine

   Turn off the engine, disconnect the battery, and allow the exhaust system to cool completely.

2. 2

   Locate the Sensor

   Locate the Lambda sensor on the exhaust pipe (typically mounted near the DOC - Diesel Oxidation Catalyst or SCR unit).

3. 3

   Disconnect

   Unplug the sensor's electrical connector from the main engine harness.

4. 4

   Remove the Sensor

   Use a dedicated O2 sensor socket (usually 22mm or 7/8") to remove the sensor. Note: Because of extreme exhaust heat, the threads may be seized. Penetrating oil and a breaker bar may be required.

5. 5

   Prepare the New Sensor

   Check the threads of the new OEM sensor. If it does not have anti-seize compound pre-applied, apply a small amount of sensor-safe, high-temp anti-seize to the threads (do not get any on the sensor tip).

6. 6

   Install

   Thread the new sensor in by hand to prevent cross-threading, then torque to the manufacturer's specification (usually around 30-35 lb-ft).

7. 7

   Reconnect

   Plug the electrical connector back in. Ensure the wire is routed safely away from direct contact with the hot exhaust pipe using high-temp zip ties or factory clips.

8. 8

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use your diagnostic tool to clear fault code 19560. Start the engine and verify the code does not return.