BRACKET-EXHAUST 3818040 - Caterpillar

During operation, the oxygen sensor may reach temperatures that exceed 700 °C (1292 °F). Severe personal injury and property damage will result from contact with a hot oxygen sensor.Do not touch the sensor during engine operation, calibration, or testing. Allow the sensor to cool before moving the sensor. Wear gloves that resist heat. Do not place the sensor on or near any flammable material or any surface that can be damaged by high temperatures.
Ensure that the electrical power has been removed from the engine.
Remove the suspect sensor from the exhaust system.
Turn the engine control to STOP.
Allow several minutes for the heating element to heat. Use an infrared thermometer to check the temperature at the tip of the oxygen sensor.The heating element will heat the tip of the sensor to approximately 600° C to 800° C (1100° F to 1500° F).
Remove electrical power from the engine.Expected Result:The heating element is heating the tip of the sensor to the specification that is given above.Results:
OK - The heating element is heating the tip of the sensor to 600° C to 800° C (1100° F to 1500° F). The heating element is OK. Proceed to Test Step 6.
Not OK - The tip of the sensor is not heating to the correct temperature. There is a problem with the heating element. The sensor may not be receiving the correct supply voltage. Proceed to Test Step 3.Test Step 3. Measure the Voltage from the Buffer at the Sensor Connector
Disconnect the sensor connector that is between the sensor and the sensor buffer.
Set the engine control to STOP.
Use a multimeter to measure the voltage between terminal 1 (12 VDC) and terminal 2 (return) on the connector for the buffer. This connector is between the sensor and the sensor buffer.
Remove electrical power from the engine.Expected Result:12 V is available at the sensor connector.Results:
OK - 12 V available at the sensor connector.Repair: Supply voltage is available to the oxygen sensor. The heating element is not heating the sensor, but the sensor is receiving the correct voltage. There is a problem with the sensor. Replace the sensor.STOP
Not OK - 12 V is not available at the terminals of the sensor connector between the sensor and the sensor buffer. The supply voltage is not available at the sensor. There may be a problem with the sensor buffer or there may be a problem with the voltage converter. Proceed to Test Step 4.Test Step 4. Measure the Voltage from the Voltage Converter at the Harness Connector for the Sensor Buffer
Disconnect the harness connector that is between the sensor buffer and the voltage converter.
Set the engine control to STOP.
Use a multimeter to measure the voltage between terminal 1 (12 VDC) and terminal 2 (return) at the sensor buffer. This measurement is taken on the harness side of the connector.
Remove electrical power from the engine.Expected Result:12 V available at the terminals of the harness connector at the sensor buffer.Results:
OK - There is 12 V available to the sensor buffer.Repair: Supply voltage is available