What is the purpose of a secondary air pump?

[LeEthan]

The secondary air pump functions to inject air into the exhaust manifold after a cold engine start. Its purpose is to enable the incomplete combustion of the air-fuel mixture to undergo a second combustion process within the exhaust pipe, thereby reducing emissions and meeting current stringent environmental requirements. The working principle of the secondary air pump involves driving the air pump via the crankshaft belt when the engine is running, pumping a large volume of low-pressure air through a hose into the diverter valve. The secondary air system is one of the external purification devices designed to reduce exhaust emissions. By introducing additional air into the exhaust gases, it increases the oxygen content, allowing unburned harmful substances such as carbon monoxide and hydrocarbons to undergo further combustion under high-temperature conditions.