Sometimes it can take a day or two, but if you're sure a loose gas cap is why it went on, don't worry about it - it will go out.
100 to 150 miles
Not as long as the computer detects a problem
yes
Whether or not a car will pass inspection with the Check Engine light on is up to the state or county giving the test. As long as the car passes an emissions test, it should be fine.
Until the problem causing the check engine light to go on is fixed. It might not be the gas cap, or the one you replaced it with could be wrong.
Have vehicle scanned to determine the problem take it to autozone they will hook up there hand held computer to it and tell you what is wrong as long as the check engine light is on and its free
That depends on how long it takes the computer to run the self diagnostics that check the failed component. could be back on in seconds or weeks.
Not very long, as it will just come right back on.
It is not recommended, the check engine light will come on, and in the long run the engine will sludge up.
you do not fix the light. you fix what ever caused the light to come on. so the lenght of time depends on the cause for the light to go on on the first place.
Have the computer checked for stored codes. This will give a clue as to which sensor is triggering the "check engine" light. Many auto parts stores will check the codes for you at no charge.
This is not a question that someone should be asking as there are numerous trouble codes that will illuminate the check engine light. You dont "replace" the check engine light. You fix what's causing the light to come on, then reset the engine computer by pulling the main fuse under the hood. If you've properly taken care of the problem causing the light to come on then the light won't re-light. It's always best to reset the engine computer as a first step as sometimes the engine will do something to illuminate the light then resolve itself. Normally on an older Civic the cause is a worn out O2 sensor.