Hyundai vehicles use two sensors on their vehicles. An oxygen sensor is an electrical component that measures the amount of contaminants in the exhaust gases being emitted from the vehicle. This information is gathered and sent to the Hyundai vehicle's electronic control module. The module, called an ECU, can then adjust the air to fuel mixture so that the vehicle is optimizing the amount of fuel it consumes. When these sensors fail, you will notice a dramatic decrease in engine performance. You need to change the sensors, but first, you have to find them.
Jack the Hyundai off the ground. Place jack stands under the front pinch welds under the driver and passenger side doors and lower the vehicle onto the stands.
Climb under the front of the Hyundai. Look directly behind the engine. There will be a section of exhaust tubing called a manifold that is bolted to the back of the engine. One of the Hyundai's oxygen sensors will be mounted there on the exhaust piping. This is called an "upstream oxygen sensor."
Slide towards the middle of the Hyundai. Look at the large, elongated "egg shaped" component that is bolted inline with the exhaust piping. This is the Hyundai's catalytic converter. Just behind the converter is the second oxygen sensor. This is called the "downstream oxygen sensor."
