Secondary Air Injection Pump. Smog Pump.
An 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.

Secondary Air Injection Pump

2.5 LITER. A3; 2.0L. Beetle; 2.5L. CALIFORNIA. CC; 2.0L. Convertible, 2.5 LITER. Coupe, 2.5 LITER. ENGINE AREA. Eos; 2.0L. Golf. GTI. Jetta Wagon; 2.0L. Jetta Wagon; 2.5L. Jetta; 2.0L. Jetta; 2.5L. Passat; 2.5L; Engine Code CBUA. Rabbit. RS 5. SECONDARY AIR PUMP; Beetle; 1.8L. SECONDARY AIR PUMP; Beetle; 2.0L. SECONDARY AIR PUMP; Beetle; 2.5L. SECONDARY AIR PUMP; GTI; Engine Code CBFA. SEDAN, 2.5 LITER. WAGON, 2.5 LITER.
Air Injection System Air Pump - Repair or Replace
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 Volkswagen to operate inefficiently and produce higher emissions. Our technicians have access to manufacturer-approved repair processes and Volkswagen genuine parts.