What is barometric pressure (BARO)?

barometric pressure (BARO)

Glossary “barometric pressure (BARO)” Definition:
The pressure exerted by the weight of the earth’s atmosphere, equal to one bar, 99.97 kPa, or 14.5 psi at sea level. Barometric pressure changes with the weather and with altitude. Since it affects the density of the air entering the engine and ultimately the air/fuel ratio, some computerized emissions-control systems use a barometric pressure sensor so that the spark advance and (EGR) valve flow can be regulated to control emissions more precisely.