Lexus 89467-33090 Sensor, Air Fuel Ratio

The manufacturer refers to the upstream sensor as the air-fuel ratio sensor and the downstream sensor as the oxygen sensor. When replacing the oxygen sensor, it may be difficult to loosen when the engine is cold. To avoid damaging the sensor, start and run the engine for a minute or two before attempting to loosen it. Disconnect the cable from the negative battery terminal before starting the replacement process. For the downstream sensor(s), raise the vehicle, remove the lower engine cover, and unplug the electrical connector. For the upstream sensor, it can be replaced without raising the vehicle. Unplug the sensor electrical connector and unscrew the sensor from the exhaust manifold(s) or exhaust pipe using a slotted socket. Apply anti-seize compound to the threads of the sensor and ensure new sensors already have this compound coated. If reusing an old sensor, recoat the threads. Install the sensor, tighten it securely, and reconnect the electrical connector.