The Hyundai oxygen sensor is a mandated device by the US government for the vehicle to be legally operated on the roads in America. It is also incorporated into the fuel system so the changes in altitude the vehicle might experience can be compensated for. The location of the Hyundai oxygen sensor is on the exhaust pipe just after the exhaust manifold. It can be identified by the wire leading from it. The oxygen sensor's function on your Hyundai vehicle is to measure the difference between the atmospheric oxygen levels and what is present in the exhaust gases your engine is producing. This is registered as a ratio, not absolute measurements. The ratio is sent to the onboard computer so the correct adjustment to the air to fuel ratio prior to combustion can be made. This will help the engine perform at its optimum level independent of what altitude you are currently at. The failure of the oxygen sensor is a problem, and a Hyundai Driver will be informed by the onboard computer turning on the dash board check engine light. To properly identify this problem, the code from the computer will have to be retrieved. The oxygen sensor failure along with all of the other sensors has a specific code that the computer will produce. These codes are available to the Hyundai owners. The replacement of the oxygen sensor is easy and can be accomplished by the owner. The first step is to disconnect the battery. This will remove the energy to the old sensor along with the clearing of the code in the computer. This will also remove all of the stored codes in the computer so if there is more than one, they should be recorded and investigated what they mean before the battery is disconnected.