Where is the secondary air valve located on the Passat?

[Sara]

The secondary air valve of the Passat is located inside the cover above the air filter box. The secondary air pump is positioned at the lower front part of the air filter box (closer to the front of the car), connected to the lower front of the air filter box via a plastic tube approximately 3 cm in diameter. Introduction to the secondary air system: The secondary air system is one of the external purification devices designed to reduce exhaust emissions. It is used for exhaust reprocessing during the engine warm-up phase. In this process, fresh air is directly blown into the exhaust manifold to heat the exhaust catalytic converter more quickly. The engine controls the secondary air pump through the secondary air pump relay. Function of the secondary air system: When the engine is cold, the system delivers air to the three-way catalytic converter. This allows the exhaust gases to react with the oxygen in the air for secondary combustion, thereby increasing the temperature of the three-way catalytic converter. This helps the three-way catalytic converter reach its operating temperature more quickly and enter its working state, reducing the emission of harmful substances in the exhaust and serving an environmental protection purpose.