How does the secondary air pump work on a Peugeot 307?

The secondary air pump on a Peugeot 307 helps to reduce emissions during cold start conditions by injecting fresh air into the exhaust system. This additional air enhances the combustion of unburned fuel in the exhaust, allowing for more complete oxidation of hydrocarbons and carbon monoxide. The pump is activated by the engine control unit (ECU) when the engine is cold, typically during the first few minutes of operation. Once the engine reaches optimal operating temperature, the pump is deactivated.