Genuine Audi - Secondary Air Injection Pump Right 1.8T - TT Mk1An emissions component, that is part of the Secondary Air Injection system, which is responsible for Pumping clean Air into the vehicle's exhaust stream to promote a cleaner and more complete burn before the fumes exit the tailpipe. A failed air injection pump or secondary air pump will often have no noticeable symptoms beyond a check engine light, but it does cause your Mk1 1. 8T Audi TT to operate inefficiently and produce higher emissions.