Toyota 89465-06030 Oxygen Sensor

To check the oxygen sensor, locate the electrical connector and insert pins into the signal and ground terminals, then use a voltmeter to monitor the voltage signal as the engine warms up. The sensor should fluctuate between 0.1 to 0.9 volts in closed-loop mode. Inspect the heater resistance and verify it is receiving battery voltage. If the sensor fails any tests, replace it. To replace the sensor, disconnect the battery, unplug the electrical connector, unscrew the sensor from the exhaust manifold, apply an anti-seize compound to the threads, and install the new sensor. The air/fuel sensor cannot be checked for voltage without a special tool, but the resistance of the heating element can be checked with an ohmmeter. To replace the AF sensor, disconnect the battery, unplug the electrical connector, unscrew the sensor from the exhaust manifold, apply anti-seize compound to the threads, and install the new sensor.

The PCM responds to the sensor signals by constantly altering the pulse width of the fuel injectors to maintain an air-to-fuel mixture ratio of 14.7 to 1 at all times.

The PCM will set a diagnostic trouble code if this condition occurs at 1,500 or more rpm after the engine reaches normal operating temperature.

Because the A/F sensor is installed in the exhaust manifold or pipe, which contracts when cool, it may be difficult to loosen when the engine is cold. Run the engine for a minute or two before attempting to remove it.

The purpose of On-Board Diagnostics II (OBD-II) engine management systems in vehicles is to verify the accuracy of the basic feedback loop between the oxygen sensor and the PCM.