What is a manufacturer auxiliary emission control system?

A manufacturer auxiliary emission control system (MAECS) is a device or system that is used to control emissions from a motor vehicle engine that is not part of the original equipment of the vehicle. MAECS are typically used to reduce emissions of hydrocarbons (HC), carbon monoxide (CO), and/or nitrogen oxides (NOx).

Some common types of MAECS include:

* Catalytic converters: Catalytic converters use a catalyst to convert HC, CO, and NOx into less harmful substances, such as water vapor and carbon dioxide.

* Oxygen sensors: Oxygen sensors measure the amount of oxygen in the exhaust gas and send this information to the engine's computer, which then adjusts the fuel mixture to reduce emissions.

* Exhaust gas recirculation (EGR) systems: EGR systems recirculate a portion of the exhaust gas back into the engine, which helps to reduce combustion temperatures and emissions of NOx.

* Positive crankcase ventilation (PCV) systems: PCV systems vent crankcase gases back into the engine, which helps to reduce emissions of HC.

MAECS are required to meet certain standards set by the United States Environmental Protection Agency (EPA). These standards are designed to ensure that MAECS are effective in reducing emissions and do not cause any adverse effects on the vehicle's performance or safety.