Car Mechanics (UK)
Fitted to every new petrol car by law since the early 1990s, three-way regulated catalytic converters have proven to be very reliable. They work by converting harmful nitrogen oxide, carbon monoxide and hydrocarbons into, primarily, nitrogen, carbon dioxide and water.
As the precious platinum/ rhodium/palladium metals that coat the delicate honeycomb structure within the converter (as shown) do not change themselves, they are very longlasting. However, they are not tolerant of sudden impacts or rapid cooling (such as driving though flood water).
‘Cat theft’ has also become an issue, due to high scrap prices, especially on taller vehicles. As a number of replacement aftermarket converters contained hardly any precious metals, to keep the price down, it became a legal requirement for all catalytic converters to meet certain standards, be Type Approved and wear the appropriate E-marks. Even so, counterfeit converters can still be bought, especially for older cars that were popular before the Type Approval requirement became law, so be wary of very cheap offerings available online, in particular.
Most diesel cars have been fitted with unregulated oxidising catalytic converters for more than 20 years. These play an extra function on cars equipped with DPFS, because they promote an exothermic reaction that helps to increase DPF temperatures and this facilitates soot combustion.