How do you replace the oxygen sensor on the Toyota sequoia?

Answer 1

This references the 2001 Toyota Sequoia:

There are four O2 sensors on the Toyota Sequoia.

There are two exhaust systems on the Toyota Sequoia: one is located under the drivers side and the other is located under the passengers side. Each exhaust system has a catalytic converter on it.

There are two O2 sensors on each exhaust system: one O2 sensor is installed in front (engine side) of the catalytic converter and one behind the converter.

The O2 sensors are referenced by 1) Bank - which side it's mounted on and 2) whether it's the front or back sensor.

Bank 1 references the drivers side exhaust system.

Bank 2 references the passenger side exhaust system.

Sensor 1 is in front of the catalytic converter (nearest the engine).

Sensor 2 is behind the catalytic converters.

Each sensor is referred to by their position on the vehicle i.e.: bank 1 sensor 1 describes drivers' side, engine side of the catalytic converter.

You have to access these sensors from under the car.

The O2 sensors are screwed into threaded plates welded onto the exhaust piping. They are all electronically connected within a few inches of the sensor with environmental plugs.

The rear sensors are fairly easy to remove and the front ones are more difficult. The bank 1 sensor 1 (driver's side, forward) is extremely difficult to access and sometimes requires the owner taking the vehicle to a Toyota service center for replacement. Note that an estimate at a Little Rock Arkansas dealer was ~$800 to replace that sensor in 2009 due to having to remove the header to access the sensor.

Toyota Sequoia sensors are very expensive as compared to many other vehicles.