The Pierburg Air Injection Check Valve (part number 705817090) is a component used in the air injection system of a vehicle's engine. It is responsible for regulating the flow of air into the engine, which helps to improve fuel efficiency and reduce emissions. The check valve is made by Pierburg, a leading manufacturer of automotive components, and is designed to meet the highest quality and performance standards. It is a crucial part of the air injection system and plays an important role in maintaining the overall health and performance of the engine.