Catalytic Converter: Description and Operation

Three Way Converter Cutaway:

Caution
Prolonged operation with a misfiring or flooded engine may cause the converter to overheat. This could cause damage either to the catalyst itself or the operating vehicle and possible personal injury.

Note
When jacking or lifting vehicle from frame side rails, be certain lift pads DO NOT contact catalytic converter or damage to converter may result.

Description
The catalytic converter is an emission control device added to the exhaust system to effectively reduce the levels of carbon monoxide, hydrocarbons, and oxides of nitrogen, entering the atmosphere. The converter serves two purposes: it permits a faster chemical reaction to take place and although it enters into the chemical reaction, it remains unchanged, ready to repeat the process.

Heat Shields
This device sometimes requires the use of heat shields, due to its high operating temperatures. The heat shields are necessary to protect chassis components, passenger compartment and other areas from heat related damage.

Dual Bed TWC
This model Cadillac uses a dual bed monolith type three-way catalytic convertor. The first bed is a reduction type and the second is the oxidation type. The oxidation catalyst is coated with material containing platinum and palladium which lowers levels of carbon monoxide and hydrocarbons. The reduction catalyst is coated with platinum and rhodium which lowers levels of oxides of nitrogen (NOx), as well as carbon monoxide and hydrocarbons.

Fill Pipe Restrictor
A fill pipe restrictor is used on catalytic converter equipped vehicles, to prevent the larger service station pump nozzle, used for leaded fuels, being inserted into the filler tube. Since the use of leaded fuels contaminates the catalysts, rendering them ineffective, the use of unleaded fuels is mandatory in catalytic converter equipped vehicles.