The is a small, metallic box located near the front of your car’s exhaust system. It helps to reduce harmful emissions and has to be replaced every 100,000 km or so.
The contains a honeycomb of ceramic or metal granules coated with platinum, palladium and rhodium. It’s there to help reduce the poisonous emissions from your car’s engine by mixing unburnt fuel and air in the exhaust with incoming fresh air and subjecting them both to extreme heat (about 600 degrees Celsius). That causes a chemical reaction that transforms carbon monoxide into carbon dioxide, which is less toxic, and hydrocarbons into water vapor through oxidation.
Platinum works best when catalyzing this reaction because it has one of the highest boiling temperatures of all metals at 2,204 degrees Celsius, so it helps transfer enough heat to achieve these high temperatures quickly. Platinum also has low levels of oxides on its surface.
A car’s catalytic converter starts working as soon as you start your engine. If it doesn’t, check its fuses first. Then, disconnect the battery because there could be a short circuit or other electrical problem. You should also visually inspect all related wiring for signs of melting or fire damage through holes in the insulation because that could indicate there is an electrical fault. Once you have isolated any problems and fixed them, start the car again to see if the catalytic converter has started working within 30 seconds. If not, call a mechanic to investigate further.
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