Case IH 3710 – ENGINE: Lambda Sensor: Fault to Indicate Dynamics of the Sensor Signal Too Small

The engine control system has detected that the oxygen (Lambda) sensor is responding too slowly or its signal fluctuations are too weak. This typically points to a sluggish, fouled, or failing sensor that can no longer accurately measure the oxygen content in the exhaust stream.

• skid steer
• Farmall 75C
• Farmall 115U Pro EP
• Maxxum
• Puma
• Steiger
• SSL (Skid Steer Loaders)
• CTL (Compact Track Loaders)

1. 1

   Inspect the Lambda sensor's wiring harness and the main engine harness connector for chafing, melting, corrosion, or loose pins.

2. 2

   Check the exhaust system for leaks upstream or immediately downstream of the Lambda sensor, which can introduce outside air or dilute exhaust gas.

3. 3

   Remove the sensor and visually inspect the tip for heavy soot, carbon fouling, or contamination from burning oil or coolant.

4. 4

   Use a diagnostic tool to monitor the Lambda sensor's live voltage/current data to verify if it responds properly to sudden changes in engine RPM and load.

1. 1

   Cool down exhaust

   Park the machine on a level surface, turn off the engine, and allow the exhaust system to cool completely to prevent severe burns.

2. 2

   Locate sensor

   Locate the Lambda sensor on the exhaust pipe (typically mounted near the turbocharger outlet or the DPF/DOC emissions assembly).

3. 3

   Disconnect connector

   Disconnect the sensor's electrical connector from the engine wiring harness.

4. 4

   Remove sensor

   Using a specialized O2 sensor socket (usually 22mm or 7/8") or a suitable wrench, carefully loosen and remove the faulty Lambda sensor from the exhaust pipe.

5. 5

   Clean threads

   Clean the mounting threads in the exhaust pipe to ensure the new sensor seats correctly.

6. 6

   Apply anti-seize

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-coated from the factory). Caution: Do not get any anti-seize on the sensor tip, as this will instantly ruin it.

7. 7

   Install new sensor

   Thread the new Lambda sensor into the exhaust pipe by hand to prevent cross-threading, then tighten it to the OEM torque specification.

8. 8

   Reconnect connector

   Reconnect the electrical connector, ensuring the wire is routed safely away from extreme heat sources and moving parts.

9. 9

   Clear fault code

   Connect a diagnostic tool to clear the stored 3710 fault code from the Engine ECU, then run the engine to operating temperature to confirm the code does not return.