The 2002 Toyota Camry used two types of heated oxygen sensors. Wide-band sensors were used upstream, or before the catalytic converter, and narrow-band sensors were used downstream, or after the catalytic converter. The wide-band sensor -- also known as the air-to-fuel ratio sensor -- measures and adjusts for the optimum ratio of gasoline-to-oxygen being delivered to the fuel injectors. The narrow-band -- or standard heated oxygen sensor -- measures the amount of pollutants in the vehicle's exhaust. A Camry with the 2.4-liter engine used a single air-to -fuel ratio sensor upstream of the catalytic converter and one heated oxygen sensor downstream of the catalytic converter. A Camry with the 3.0-liter V-6 engine utilized two air-to-fuel ratio sensors upstream and two heated oxygen sensors downstream of the catalytic converter. Both types of sensors are equipped with four-wire pigtail connectors. There is a blue signal wire, a white ground wire and two black wires that control the heated portion of the sensor.
Spray the defective sensor still mounted in the engine's exhaust with a penetrating oil. Allow it to soak for 24 hours.
Park the vehicle on a level surface and apply the parking brake. If replacing a downstream oxygen sensor it may be necessary to raise the front of the vehicle and support with jack stands. Upstream sensors can often be accessed from the engine compartment.
Press the disconnect tab on the sensors pigtail connector and carefully separate the sensor connector from the harness connector.
Using the oxygen sensor socket and ratchet, or a 22 mm open-end wrench, remove the oxygen sensor from the exhaust by turning the sensor counterclockwise.
If replacing with an exact fit pigtail connector, apply anti-seize compound to the threads of the new sensor -- don't get any on the tip -- and install it by turning the sensor into the exhaust. Tighten the sensor to 30 foot-pounds. Connect the pigtail connector to the harness connector.
If you're replacing with a universal oxygen sensor, follow the manufacturer's instructions on how to cut and splice the old pigtail connector to the new sensor. Be sure to match wire colors and function according to the manufacturer's color reference chart.
Apply anti-seize compound to the threads of the new sensor and install it into the exhaust. Tighten the sensor to 30 foot-pounds. Connect the pigtail connector to the harness connector.
Remove the jack stands, lower the vehicle and release the parking brake. Test drive the vehicle -- if the check engine light was illuminated it may take several drive cycles for the light to go out once the new sensor has been installed.
