The catalytic converter converts pollutants in the exhaust system into less toxic pollutants by using a redox reduction method. The catalytic converter is located on the exhaust system of your vehicle, and is essential to controlling your vehicle’s emissions. It basically burns the emissions and converts them into water vapor and oxygen. The main emissions of your vehicle include nitrogen gas, carbon dioxide (CO2), water vapor( H2O), carbon monoxide (CO), hydrocarbons (VOC), and nitrogen oxides (NO and NO2).

Most modern vehicles are equipped with a three-way catalytic converter. The first stage of the catalytic converter is the reduction catalyst. In this stage, rhodium and platinum reduce the nitrogen oxide emissions. The second stage is the oxidation catalyst. Here, the unburned carbon monoxide and hydrocarbons are reduced by burning them over palladium and platinum catalyst. The control system is the third stage and it monitors the exhaust stream. It uses this information to control the fuel injection system through an oxygen sensor. The sensor will send information to the engine about how much oxygen is in the exhaust. If there is too much or too little oxygen, the engine’s computer can increase or decrease the amount by adjusting the air to fuel ratio. This ensures there is enough oxygen in the exhaust to make certain the oxidation catalyst can burn the carbon monoxide and hydrocarbons effectively.

The catalytic converter works at an extremely high temperature, so it is not uncommon for it to fail. For example, a misfiring engine system can cause the catalytic converter to overheat and become damaged. In addition, exhaust can become trapped in the catalytic converter, which creates back pressure and causes the engine to stop running. This will cause your vehicle to stall while you are driving. The catalytic converter can also be damaged due to impact from road debris. Watch for the following signs that indicate your catalytic converter is failing:

  • Poor fuel economy
  • Vehicle is performing poorly, such as stalling while driving or a jerking feeling
  • Misfiring engine
  • Check Engine Light
  • Rotten egg smell

Since the catalytic converter can become damaged or fail over time, the catalytic converter may need to be replaced.

This article originally appeared on YourMechanic.com as How Long Does a Catalytic Converter Last? and was authored by Valerie Johnston.


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