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.
For most drivers it means a trip to your local mechanic. This light can mean a costly problem like a bad catalytic converter or oxygen sensor or it could be as simple as a loose gas cap. Do not confuse the service required light on the gauge cluster for the Check Engine light. These warning lights are unrelated. The service required light just means the car is due for an oil change or other routine maintenance. It is not the indicator of trouble that the Check Engine light is.