New Holland ENG 3707 – Engine Control Module (ECM / EDC): Lambda sensor: Open circuit at the lambda sensor Nernst cell pin.

The engine controller has detected a complete break in the electrical circuit (an open circuit) specifically on the pin that communicates the Nernst cell's voltage signal back to the computer.

• L220
• L230
• L-Series
• C-Series
• SR175
• T4 Series
• T4.95
• T4.105
• T6
• T7
• T8
• T9 series
• CR series
• CR9090
• CX series
• CX8080
• CX8090 Elevation

1. 1

   Inspect the wiring harness running from the Lambda sensor on the exhaust system to the Engine Control Module (ECM) for chafed wires, melted insulation, or physical breaks.

2. 2

   Disconnect the Lambda sensor and inspect both sides of the connector for corrosion, moisture, or pushed-out pins.

3. 3

   Using a multimeter, check for continuity on the signal wire (Nernst cell pin circuit) between the Lambda sensor harness connector and the ECM connector. Infinite resistance indicates a harness break.

4. 4

   If the harness tests good, the open circuit is internal to the Lambda sensor itself (a failed Nernst cell or internal wire break).

1. 1

   Power Down

   Turn off the machine and disconnect the battery via the master disconnect switch to prevent electrical spikes.

2. 2

   Remove the Sensor

   Disconnect the Lambda sensor wiring harness connector. Using an O2 sensor socket or wrench, carefully unthread the Lambda sensor from the exhaust pipe/DPF assembly.

3. 3

   Install the New Sensor

   Apply a small amount of anti-seize compound to the threads of the new sensor (if not pre-applied by the manufacturer). Thread it into the exhaust and tighten to OEM torque specifications.

4. 4

   Reconnect

   Plug the sensor connector back into the engine wiring harness. Reconnect the battery.

5. 5

   ECU Reset

   Connect the New Holland Electronic Service Tool (EST), navigate to the Configuration Items window, and execute the "Reset ECU data (Lambda sensor)" procedure.

6. 6

   Clear Codes

   Clear the inactive ENG 3707 fault code and run the engine to verify the code does not return.