Case IH 3722 – ENGINE: Lambda Sensor: LSU sensor temperature Ri exceeds the maximum limit.

The internal resistance (Ri) temperature of the Lambda (Oxygen) sensor has exceeded its maximum allowable threshold. This condition points to an overheating sensor, an internal sensor failure, or an issue with the LSU heater power stage.

• skid steer
• Farmall 115U Pro EP
• Steiger
• Puma
• Maxxum
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SV250
• SR175

1. 1

   Check for related codes (such as 3724 or 3725) that might indicate a wiring issue rather than a failed sensor

2. 2

   Inspect the Lambda sensor's 5-pin wiring harness and connector for signs of melting, corrosion, or open circuits

3. 3

   Verify that the exhaust system does not have restrictions or abnormal combustion conditions causing excessive exhaust gas temperatures

4. 4

   Use the Electronic Service Tool (EST) to monitor the Lambda sensor's temperature and resistance readings in real-time

1. 1

   Preparation

   Turn off the engine and allow the exhaust system to cool completely to avoid burns. Disconnect the negative battery cable.

2. 2

   Locate the Sensor

   Locate the Lambda sensor on the exhaust system (typically positioned before the catalytic converter or DPF).

3. 3

   Removal

   Disconnect the electrical connector for the Lambda sensor. Using an O2 sensor socket, carefully unscrew the sensor from the exhaust pipe.

4. 4

   Installation

   Apply a small amount of anti-seize compound to the threads of the new sensor (if not pre-applied), ensuring no compound touches the sensor tip. Thread the new sensor into the exhaust pipe by hand, then tighten to the manufacturer's specified torque.

5. 5

   Reconnection

   Reconnect the electrical harness and the negative battery cable.

6. 6

   ECU Reset

   Connect the diagnostic service tool (EST). Clear the fault codes and perform the 'Reset ECU data (Lambda sensor)' procedure to restore self-learning parameters for the new sensor.