Front Sections
| Item Number | Description |
|---|---|
| 1 | Flange |
| 2 | Inlet pipe |
| 3 | Heated Oxygen Sensor (HO2S) boss |
| 4 | Outlet pipe |
| 5 | Catalytic converter |
Each of the front sections consists of an inlet pipe, a catalytic converter and an outlet pipe welded together. A flange on the inlet pipe connects the front section to the related exhaust manifold on the engine. The flange has two holes which locate on studs in the exhaust manifold and is secured with flanged nuts.
In the catalytic converters, the exhaust gases are passed through honeycombed ceramic elements coated with a special surface treatment called 'washcoat'. The washcoat increases the surface area of the ceramic elements by a factor of approximately 7000. On top of the washcoat is a coating containing palladium and rhodium, which are the active constituents for converting harmful emissions into inert by-products. The palladium and rhodium take oxygen from nitrogen oxides, to leave nitrogen, and combine the oxygen with carbon monoxide and hydrocarbons to leave carbon dioxide and water.