Case IH 3716 – Engine Control Unit (ECU): Lambda sensor: O2 value above the max threshold.

The Lambda (Oxygen/O2) sensor is detecting an oxygen concentration in the exhaust gas that exceeds the maximum allowable limit programmed into the control module.

• Farmall
• Farmall 115U Pro EP
• Farmall 60A
• Farmall 70A Tier 4
• Puma 210
• Steiger
• Maxxum
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)

1. 1

   Inspect for unmetered air entering the exhaust system (exhaust leaks prior to the sensor) or severe intake leaks causing a lean condition

2. 2

   Inspect the sensor wiring harness and 5-wire oval plug (6 pins) for chafing, corrosion, or loose pins

3. 3

   Verify that the LSU sensor heater power stage is receiving proper battery voltage

1. 1

   Resolve Mechanical Leaks

   If any exhaust leaks or intake anomalies are found during the visual inspection, repair them first, as they will artificially drive up the O2 readings.

2. 2

   Repair Wiring

   Fix any damaged wires or replace the connector pigtail if voltage drops or shorts are discovered.

3. 3

   Replace the Sensor

   If the wiring is intact and no mechanical leaks are present, the Lambda sensor itself has likely failed or degraded. Remove the old sensor from the exhaust system and install the replacement.

4. 4

   Clear Codes

   Use the Electronic Service Tool (EST) or equivalent diagnostic scanner to clear the active 3716 fault code from the Engine ECU.

5. 5

   Test Run

   Cycle the key and run the engine to operating temperature to verify that the O2 values remain within the normal threshold and the code does not return.