A catalytic converter is an exhaust emission control device that reduces toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalysing a redox reaction (an oxidation and a reduction reaction). Catalytic converters are usually used with internal combustion engines fuelled by either gasoline or diesel. To ensure that you get the correct catalytic converter, it is best to check the size and shape of the one currently installed so you can compare with the listed cats. Some important information for selecting the correct Lambda sensor is the basic year, make, model and engine type, as well as the transmission type or sub-model. The EFN (short for “Engine Family Number”) is a number given to your specific engine which identifies both the engine and your vehicle’s emissions, which is also useful for selecting the correct cat converter. If your vehicle was manufactured post-1995, it will have an EFN. The EFN can be found on the Vehicle Emissions Control Information (VECI) label, usually found in the engine bay.