What is a Catalytic Converter?

A Catalytic Converter (or Cat) is an Exhaust Emissions Device located underneath a vehicle. It uses a combination of heat and precious metals to promote a chemical reaction, which breaks down harmful gases, making the emissions less detrimental to the environment.

How Does a Catayltic Converter  Work?

The operating temperature of a cat is between 350 to 400 degrees Celsius. Once the catalytic converter has reached this temperature a chemical reaction occurs as the exhaust gases flow through the coated monolith. The harmful gases are oxidised and converted as shown in the diagram opposite.

What are the Components of a Cat?

A honeycomb monolith coated with precious metals (usually Platinum, Palladium and Rhodium) is encased in a steel can. Between the monolith and the can is matting. Upon running a cat in, this matting expands when subjected to heat. Once expanded, the matting holds the monolith in place.

Type Approved Catalysts

Due to government legislation it is now a legal requirement on vehicles registered after March 2001 (anything with a Y registration or later) to be fitted with a type approved catalytic converter. 

The difference between a non approved and a type approved catalytic converter is the amount of precious metal contained in the brick and its overall volume, the parts will look exactly the same.

The price difference in the type approved catalytic converter is due to the increase in precious metal content.

It is a legal requirement to fit the correct catalytic convertor to your car.