Mitsubishi Repair: 2006 endeavor, check engine soon light, autozone

Question
what happens if my "check engine soon" light comes on? I took the gas tank cap off and put it back on to make sure that it was tight. After a few minutes the light went off. What does that mean.

Answer
If the check engine light (MIL) comes on, it indicates that the computer found a fault. It could be a hard fault, or a performance fault, or as you tried, a gas cap that did not allow the evaporative system from holding a vacuum for a specified amount of time. The beauty of your on-board diagnostic system (OBDII) is that is retains the code in memory for 40 warm-up cycles. Simply find a place (autozone or schucks) that will pull your codes for free. Please don't allow them to "diagnose" your problem and sell you parts.  The code will indicate the nature of the problem. If you see an error code for evap leak (large), (small) or evap system performance, then it may likely have been the gascap. If it is another system, then further diagnosis will be needed.  The light went of because the system tested itself and found everything was okay.

A flashing MIL indicates a misfire that is severe enough to damage the catalyst, so immediate repair is needed then.