Case IH 19562 – Engine Control Module (ECM) or Vehicle Control Module (VCM): SRC Min error for the Linear lambda signal

This fault code indicates a 'Source Range Check Minimum' error regarding the linear lambda (oxygen/NOx) sensor. The signal voltage or current returning from the exhaust lambda sensor to the control module has dropped below the minimum acceptable threshold, which typically points to an open circuit, a short to ground in the sensor wiring, or an internal failure of the sensor element itself.

• Tier 4b
• T7 Series tractors
• Farmall series tractors
• Puma series tractors
• Maxxum series tractors
• N-Series Tractor Loader Backhoes (TLBs)

1. 1

   Visual Inspection: Inspect the wiring harness leading to the lambda/NOx sensor on the exhaust system. Look for melted wires, chafing, or physical damage caused by exhaust heat or field debris.

2. 2

   Connector Check: Disconnect the sensor and inspect the pins for corrosion, moisture, or pushed-out terminals.

3. 3

   Circuit Testing: Use a multimeter to check for an open circuit or a short to ground on the sensor signal wire returning to the ECM. Verify that the sensor is receiving the correct reference voltage and ground.

4. 4

   Exhaust Leak Check: Inspect the exhaust pipe upstream of the sensor for leaks, as introducing outside air can severely skew lambda readings and trigger plausibility or range errors.

1. 1

   Preparation

   Turn off the engine, remove the key, and disconnect the battery. Allow the exhaust system to cool completely.

2. 2

   Locate the Sensor

   Locate the lambda/NOx sensor on the exhaust pipe (typically mounted upstream of or directly on the SCR/DPF aftertreatment assembly).

3. 3

   Disconnect

   Unplug the sensor's electrical connector from the main engine harness. Free the wire from any retaining clips.

4. 4

   Removal

   Using a specialized oxygen sensor socket or a wrench, carefully unscrew the sensor from the exhaust pipe. Note: Penetrating fluid may be required if the sensor is seized from heat cycling.

5. 5

   Installation

   Apply a small amount of high-temp anti-seize compound to the threads of the new sensor (many OEM sensors come with this pre-applied; do not get anti-seize on the sensor tip). Thread the new sensor into the exhaust pipe and tighten to the manufacturer's torque specification.

6. 6

   Reconnect

   Plug the electrical connector back into the harness. Ensure the wiring is secured in its clips and routed safely away from direct contact with the hot exhaust pipe.

7. 7

   Clear Codes

   Reconnect the battery. Use a diagnostic scan tool (such as the Case IH EST) to clear the inactive 19562 fault code. Run the machine at operating temperature to ensure the code does not return.