If the problem was correctly fixed by a mechanic or yourself the check engine light should go out after a few cycles (on/off of running). A mechanic usually shuts the light off with diagnosis tools after the work is completed to check that it does not come on again due to the same error as there is no way to permanently shut the light off. If it is still on the repair done may not have been needed or there are more issues that need attention.
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.
IF that was the problem it will turn off within 3 starts of the engine. It always helps to state car type, make and year with these problems
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.
Replaced the upstream O2 sensor on a 1999 Ford Ranger 3.0 flexfuel and the check engine light went off and came back on after driving approx. 4 miles. Read code and it showed p0153 just as it did before. Is there a certain amount of time that the vehicle has to be driven before the computer will recognize that the new sensor is OK?
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.
First check and see if there are any codes in your computer that could be a bad sensor. My check engine light came on then went off for a long time but after the car had to be towed in we found a bad fuel sensor and when it was replaced the car has run fine since.
It is not recommended, the check engine light will come on, and in the long run the engine will sludge up.