New Holland ENG 3712 – Engine Control Unit (ECU) / EDC / EDC7: Lambda sensor: SCG error of the LSU heater power stage

The engine control system has detected a short to ground on the power circuit that supplies the internal heater element of the lambda sensor.

• T4
• T5
• T6
• T7
• T8
• T9
• Boomer
• Workmaster
• W50C
• W60C
• W70C
• W80C
• L-Series
• C-Series
• L230
• C238
• CR9090
• CX8080
• CX8090
• Speedrower
• LM series
• TH series

1. 1

   Inspect the wiring harness and connector leading to the lambda sensor for melted insulation, chafed wires, or pinched harnesses that could be shorting the heater power circuit directly to the chassis ground.

2. 2

   Test the oxygen sensor and harness using a high-impedance digital volt meter (DVM). Do not use a normal analogue multi-meter as it will draw too much current and burn out the sensor or give false readings.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Repair Wiring

   If the diagnostic check revealed a short to ground in the machine's wiring harness, repair the damaged section and secure it away from hot exhaust components.

3. 3

   Replace the Sensor

   If the wiring harness is intact, the short circuit is internal to the lambda sensor's heater stage. Disconnect the sensor plug, unthread the old lambda sensor from the exhaust/emissions system, and install the new sensor.

4. 4

   Module Re-flash / Reset

   After replacing the oxygen sensor, you must re-flash or reset the control module to allow the new sensor adjustments and calibrations to be learned by the ECU.

5. 5

   Clear Codes

   Reconnect the battery, turn the key on, and clear the inactive ENG 3712 fault code using a diagnostic scan tool.