New Holland ENG 3711 – Engine Control Unit (ECU) / EDC: Lambda Sensor: SCB Error of the LSU Heater Power stage

The control module has detected that the electrical circuit responsible for heating the Lambda sensor is shorted to a battery voltage source (12V).

• Boomer series
• T4 PowerStar
• T5
• T5.95
• T5.105
• T5.115
• T6
• T7
• T8
• T9 series
• CR series
• CX series
• CR9090
• CX8080
• CX8090
• L series skid steer loaders
• C series skid steer loaders

1. 1

   Inspect the wiring harness running from the Engine ECU to the exhaust Lambda sensor for melted insulation, chafing, or pinched wires that could expose the heater control wire to a 12V power source.

2. 2

   Disconnect the Lambda sensor and check the pins on both the sensor side and the harness side for corrosion, water ingress, or bent pins that could bridge the heater circuit to the power supply.

3. 3

   With the sensor disconnected and the key ON, use a multimeter to check the heater control circuit on the harness side for unintended battery voltage.

4. 4

   Measure the resistance across the heater pins on the Lambda sensor itself. If the internal heating element has failed and shorted to the sensor body or another pin, the sensor is the culprit.

1. 1

   Power down machine

   Turn off the machine, remove the key, and disconnect the negative battery terminal to prevent ECU damage.

2. 2

   Locate the sensor

   Locate the Lambda (O2) sensor on the exhaust system, typically mounted upstream of or directly on the SCR/DPF assembly.

3. 3

   Remove the sensor

   Disconnect the sensor's 5-pin or 6-pin electrical connector. Use a specialized 22mm (7/8 inch) O2 sensor socket to carefully unthread the sensor from the exhaust pipe. Penetrating oil may be required if the sensor is seized.

4. 4

   Repair wiring harness

   If diagnostic checks revealed a short in the machine's wiring harness rather than the sensor, repair the damaged wire insulation or replace the affected harness section.

5. 5

   Install new sensor

   Apply a small amount of anti-seize compound to the threads of the new sensor (avoid getting any on the sensor tip). Thread it into the exhaust by hand to prevent cross-threading, then torque to OEM specifications.

6. 6

   Reconnect components

   Plug the sensor connector back into the engine harness and secure the wire away from extreme heat sources. Reconnect the battery.

7. 7

   Clear codes and verify

   Connect a diagnostic tool (such as the CNH Electronic Service Tool) to clear the ENG 3711 fault code. Run the engine to operating temperature to verify the heater circuit functions properly and the code does not return.