Oxygen Sensor: Testing and Inspection

Oxygen Sensor Inspection:

HEATER TEST

1. Disconnect the oxygen sensor connector and connect test harness adapter MD998464 or equivalent.
2. Verify that there is continuity (approximately 15 ohms at 20 degrees C or 68 degrees F) between the oxygen sensor connector terminals 2 (red clip) and 4 (blue clip).
3. If there is no continuity replace the oxygen sensor.
4. Warm up the engine (coolant temperature greater than 85 degrees C or 185 degrees F).

Oxygen Sensor Inspection:

SENSOR TEST

1. Using a jumper wire connect oxygen sensor terminals 2 (red clip) and 4 (blue clip) to the battery positive and negative terminals respectively. Be careful! Improper connection of the terminals can destroy the oxygen sensor.
2. Connect an accurate digital voltmeter to oxygen sensor terminals 3 (white clip) and 1 (black clip).
3. Race the engine to 4,000 rpm and verify that oxygen sensor output voltage measures between 500 mv and 1 volt.
4. Allow the engine to rapidly decelerate to idle and verify that oxygen sensor output is 250 mv or less.
5. When the test is complete and the oxygen sensor has been reconnected erase the oxygen sensor fault code by disconnecting the vehicle battery for 15 seconds or longer. Caution! Do not disconnect the vehicle battery with the ignition turned or the engine running or permanent damage to the vehicle ECU may result.