Catalytic Converters have been in use in Australia since the introduction of un-leaded petrol in 1986. Three way catalytic converters are designed to convert 3 toxic substances (Oxides of Nitrogen, Carbon Monoxide and Hydrocarbons) out of vehicle exhaust emissions into non-toxic substances.

Oxides of Nitrogen are a major contributor to photochemical smog. The Catalytic Converter converts these to Nitrogen and Oxygen.

Carbon Monoxide can be fatal if inhaled. The Catalytic Converter converts this to Carbon Dioxide.
Hydrocarbons are unburned fuel. The Catalytic Converter converts these to water vapour.

Should the Catalytic Converter become damaged or worn out, these 3 toxic substances pass through the exhaust into the atmosphere. Catalytic Converters are not mufflers. They incorporate ceramic bricks into which has been embedded precious metals. As these metals are not distributed uniformly, the direction of gas flow is critical to correct operation.

Where the Catalytic Converter can be accidentally reversed, the direction of flow is indicated by an arrow on the body or heat shield. Accident damage or excessively rich air/fuel mixtures (can be caused by a fouled spark plug or faulty ignition lead) can cause the Catalytic Converter to melt down (the catalyst melts and breaks up). This can block the exhaust system causing power loss, stalling and backfiring. Most Catalytic Converter failure can be attributed to improper engine tuning, incorrect ignition timing or fouled spark plugs.