This part is listed by BMW as BMW part number 11721744490 (11-72-1-744-490) and is described as Secondary Air Pump for E36 323is 328i 328is M3 1996, 1997, 1998 (and 1999 2-door models).
The purpose of this pump is to pump fresh air into the exhaust gasses for the first few minutes the engine warms up. This is an emissions piece, aiming to help reduce unburnt fuel during cold starts. When working, this pump sounds sort of like a vacuum cleaner, sucking in air and pumping it into the exhaust. It usually only runs for 30 seconds after a cold start. When it fails, you often won't hear this "vacuum cleaner" like sound, and a check engine light will trigger with codes pointing to the secondary air system. Replacing a failed secondary air intake (SAI) pump is quite straight forward, and this OEM BMW pump can get your BMW back in emissions compliance and satisfying the check engine system. BimmerWorld Tip:
We also recommend replacing the secondary air valve when replacing this pump. The valve installs into the exhaust manifold and is also a common failure item, like the pump. The valve is BimmerWorld part number 11727540466
For questions, BMW fitment information or for assistance from one of our BMW experts, we recommend calling us at 877-639-9648.
BMW Fitments: 3 Series
E36 (92-99) > 323ic
E36 (92-99) > 323is
E36 (92-99) > 328i
E36 (92-99) > 328ic
E36 (92-99) > 328is
E36 (92-99) > M3 (96-99)