New Holland ENG 3714 – Engine Control Unit (ECU) / EDC7: Lambda sensor: Fault code to indicate SRC High error for O2 calibration

The engine control system has detected an out-of-range high signal (SRC High) during the calibration phase of the Lambda (Oxygen/O2) sensor, meaning the sensor is unable to calibrate its oxygen readings correctly.

• L220
• L228
• L318
• SR175
• SV185
• W50C
• W60C
• W70C
• W80C
• CR9090
• CX8080 Elevation
• CX8090 Elevation

1. 1

   Check the Lambda sensor wiring harness for chafing, melting, or open circuits. Inspect the pins at the sensor connector and the Engine ECU for corrosion or pushed-out pins.

2. 2

   Inspect the exhaust system (specifically around the DOC/DPF where the sensor is mounted) for exhaust leaks. An exhaust leak can introduce outside air, skewing the O2 calibration.

3. 3

   Remove the sensor and inspect the tip. Heavy soot, unburned fuel, or coolant contamination can ruin the sensor's ability to read oxygen levels.

4. 4

   Verify that the sensor is receiving proper battery voltage and ground.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the Sensor

   Locate the Lambda sensor on the exhaust aftertreatment pipe (typically near the Diesel Oxidation Catalyst / DPF assembly).

3. 3

   Removal

   Disconnect the sensor's electrical connector. Use a specialized O2 sensor socket to carefully unthread the sensor from the exhaust bung.

4. 4

   Installation

   Apply a small amount of anti-seize to the threads of the new sensor (if not pre-applied by the manufacturer). Thread the new sensor in by hand to prevent cross-threading, then torque to OEM specifications.

5. 5

   Reconnection

   Reconnect the electrical harness and the machine's battery.

6. 6

   ECU Reset

   Connect the New Holland Electronic Service Tool (EST). You must perform the 'Reset ECU data (Lambda sensor)' procedure to electronically force the ECU to recalibrate to the new Lambda sensor.