What is the EGR valve on a 1999 Buick Century do?

The EGR valve (Exhaust Gas Recirculation valve) on a 1999 Buick Century, like in most modern gasoline engines, reduces NOx (nitrogen oxides) emissions. It does this by recirculating a portion of the exhaust gas back into the engine's intake manifold.

Here's how it works:

* Exhaust Gas Recirculation: The EGR valve opens, allowing a controlled amount of exhaust gas to flow back into the intake manifold.

* Lower Combustion Temperature: This exhaust gas, which is relatively inert, mixes with the fresh air/fuel mixture. This mixture has a lower overall temperature during combustion.

* Reduced NOx Formation: Lower combustion temperatures significantly reduce the formation of NOx, a major component of smog.

In short, the EGR valve on your 1999 Buick Century is an emission control device crucial for meeting environmental regulations. A malfunctioning EGR valve can lead to increased emissions and potentially affect engine performance.