One of the more important data collection devices on your vehicle is the Toyota oxygen sensor. This is the sensor that collects data on the amount of oxygen that is present in your exhaust gas as it leaves the combustion chamber. That data is then compared to the oxygen level of the air surrounding the vehicle. The reason your Toyota can climb a mountain and not have the performance of the engine negatively affected by the thinning of the air is because of the task performed by the Toyota oxygen sensor. It is this data that the onboard computer uses to determine the correct level of air to fuel mixture that should be introduced to each of the combustion chambers on a continuous basis. The location of the oxygen sensor on your Toyota is in the exhaust system just after the exhaust manifold. It is very easy to locate since it is the only components that is electronically connected on your exhaust system. The wire that connects the oxygen sensor to the onboard computer has to remain intact at all times and not permitted to come in contact with the hot exhaust pipe or it will have to be repaired in order for the sensor to relay its data. If this connection is not present for any reason including the oxygen sensor malfunctioning, the check engine light will be illuminated on the dash panel for the driver to be aware there is a problem. The removal of the oxygen sensor is simple to do with just a wrench, but it is highly advisable for this repair procedure to be done once the engine has had time to cool off. This way the technician or owner of the Toyota will not get burned when they are working near the exhaust pipe when replacing the oxygen sensor.