The vapor pressure of a liquid is the point at which equilibrium pressure is reached, in a closed container, between molecules leaving the liquid and going into the gaseous phase and molecules leaving the gaseous phase and entering the liquid phase.n explanation of vapor pressure. Vapor pressure is constant when there is an equilibrium of water molecules moving between the liquid phase and the gaseous phase, in a closed container.
When a potential problem is detected, a dashboard warning light called a malfunction indicator light (MIL) is illuminated to alert the driver. An OBD system detects a problem well before symptoms such as poor performance, high emissions or poor fuel economy are recognized by the driver.
The correct mixture of air and fuel is necessary to maximize the engine's performance. A bad mass air flow sensor produces an error code in the car's on-board computer and will cause the check engine light to illuminate. This problem is easily diagnosed by a mechanic with computer testing equipment or by the car's owner using a digital scanner available for rent at auto parts stores.