Focus L4-2.0L DOHC VIN 5 (2003)
Bank 1 Catalyst Two HO2S Configuration
Bank 1 Catalyst Three HO2S Configuration
Underbody Catalyst
The underbody catalyst is located after the light off catalyst. The underbody catalyst may be in-line with the light off catalyst, or the underbody
catalyst may be common to two light off catalysts, forming a "Y" pipe configuration. For an exact configuration of the catalyst and exhaust system for
a specific vehicle, refer to the Exhaust System.
Three-Way Catalytic Converter
The three-way catalytic (TWC) converter contains either platinum (Pt) and rhodium (Rh) or palladium (Pd) and rhodium (Rh). The TWC converter
catalyzes the oxidation reactions of unburned HCs and CO and the reduction reaction of NOx. The three-way conversion can be best accomplished by
always operating the engine air fuel/ratio at or close to stoichiometry.
Exhaust Manifold/Runners
The exhaust manifold runners collect exhaust gases from engine cylinders. The number of exhaust manifolds and exhaust manifold runners depends on