New Holland ENG 3710 – Engine Control Unit (ECU) / EDC7: Lambda Sensor: Fault to Indicate Dynamics of the Sensor Signal Too Small

The Engine Control Unit is detecting that the Lambda (Oxygen/O2) sensor is responding too slowly or its signal amplitude is too narrow. This typically indicates a sluggish sensor that has become fouled with soot/carbon, degraded from age, or is suffering from a wiring resistance issue preventing rapid signal changes.

• T5.95
• T5.105
• T5.115
• TD5.85
• TD5.95
• TD5.105
• TD5.115
• T6 Series
• T7 Series
• Boomer T4 PowerStar
• Workmaster 60
• Workmaster 70
• CR9090
• CX8080 Elevation
• CX8090 Elevation Tier 4A
• L Series
• C Series
• L465
• Lx465
• Lx485

1. 1

   Visual Inspection: Check the Lambda sensor wiring harness and its 5-wire or 6-wire connector for melting, chafing, or corrosion.

2. 2

   Exhaust System Check: Inspect for exhaust leaks upstream of the Lambda sensor, which can introduce unmetered ambient air and skew the sensor's readings.

3. 3

   Sensor Removal & Inspection: Remove the sensor and inspect the tip for heavy soot accumulation.

4. 4

   Heater Circuit Verification: Ensure there are no accompanying heater circuit codes (such as ENG 3711, 3712, or 3713).

1. 1

   Preparation

   Turn off the engine, remove the key, and disconnect the battery. Ensure the exhaust system has completely cooled down to prevent burns.

2. 2

   Locate the Sensor

   Locate the Lambda sensor in the exhaust stream. It is typically mounted downstream of the turbocharger, often near the Diesel Particulate Filter (DPF) or Selective Catalytic Reduction (SCR) unit.

3. 3

   Disconnect

   Unplug the sensor's electrical connector from the main engine harness.

4. 4

   Removal

   Using a specialized 22mm (7/8") O2 sensor socket, carefully unthread the Lambda sensor from the exhaust pipe.

5. 5

   Preparation for New Sensor

   Check the threads on the exhaust bung and clean them with a thread chaser if necessary. If not pre-applied, apply a small amount of high-temp sensor-safe anti-seize to the threads only.

6. 6

   Installation

   Thread the new sensor in by hand to prevent cross-threading, then tighten to the manufacturer's torque specification using the O2 sensor socket.

7. 7

   Reconnect

   Route the wiring harness away from extreme heat sources and reconnect the plug.

8. 8

   Clear Codes

   Reconnect the battery, use a CNH diagnostic tool to clear the ENG 3710 fault code, and run the machine under load to verify the sensor dynamics are reading correctly.