In the exhaust system is a Saturn Oxygen Sensor for the purpose of data collection. This data collected by the oxygen sensor is the level of oxygen that the engine is producing as compared to what is present in the atmosphere around the Saturn vehicle.
For the most accurate reading the oxygen sensor is placed in the exhaust system just aft of the exhaust manifold before the catalytic converter. This data is sent to the on board computer for use in the calculation that determines the correct air to fuel ratio which is used in the combustion chamber of your Saturn engine.
When no signal is being sent from the Saturn oxygen sensor to the on board computer, the check engine light will become illuminated on the dashboard of your vehicle. The first thing for an owner to look for is to see if the wire connecting the senor to the rest of the system is in place and undamaged. If the wire is in place and the code retrieved from the on board computer indicates the problem is from the oxygen sensor, then a replacement sensor is required in order for the system to be restored to operational status.
Before the old oxygen sensor is removed from the exhaust pipe, not only should the engine be cooled but the battery should be disconnected. The possibility of a shock occurring during the replacement process is remote, but this precaution should still be taken. This disconnecting of the battery will also remove all of the stored codes in the on board computer. This way there will be no false reading on the dashboard of your Saturn of a faulty sensor once the repair procedure is completed and the vehicle is returned to operational status.