Secondary Air Injection System
A secondary air injection system is a major part of the emissions control system of a modern vehicle. It relies on a belt-driven or electrical pump to force some air into the exhaust system to reduce emissions.
While early secondary air injection systems were equipped with a belt-driven pump and vacuum-operated valves, most modern cars and trucks come with an electrical pump and computer-controlled valves which inject fresh air into several locations.
Powertrain control module
The key component of just about every modern secondary air injection system is a powertrain or engine control module. It is the brain of each modern vehicle, monitoring and operating fuel injection, ignition timing, and emissions control system. Depending on a vehicle, it can also operate an automatic transmission, a brake system, etc.