EMISSIONS pACKAGE
Vehicles end up with emissions problems due to various reasons. Typically if a car fails its emissions inspection you will need several items to pass. A typical emissions package includes a new catalytic converter(s), spark plugs, spark plug wires/coil packs, and new oxygen sesnors.
The main part for the emissions in any vehicle is the catalytic converter. The catalytic converter uses metal and chemical catalysts to convert the noxious gasses normally present in exhaust to less polluting gasses. Converters typically only fail if the vehicle has another issue. The majority of the time it is due to unburnt feul entering the exhaust system. This is why we reccomend replacing the oxygen sensors, spark plugs, and wires in addition to your catalytic converter if you have failed emissions as these parts are what burn the feul and tell the car's computer how much gas/air to put into the motor.
The oxygen sensor (shown above) is the part responsible for telling the motor how the car is running and also tells it how much fuel/air to put into the motor for the most fuel efficiency possible.
Spark plugs and wires (shown above) are what is actually responsible for igniting and burning the fuel/air mixture that the oxygen sensor told the computer to inject into the motor.
All these parts work together which is why we recommend doing it all if you failed an inspection.