The dreaded 'check engine light' can really ruin your day. In my circle of family and friends I find that most people overreact and end up in a panic mode, emptying their wallet at the first repair shop they can find. First, most vehicles (check your manual) have two levels of check engine warnings. The first level warning is a solid light. This means you have an issue to address but it is not an emergency. You don't need to become hysterical, swerve to the side of the road, or rush to the first mechanic you can find (If you have a flashing check engine light, you should find a safe place to park the vehicle and you are a little more justified in panicking).
What to do when the check engine light comes on
Check your temperature gauge to see if you are running hotter than normal (your temperature gauge should be right in the middle, about halfway between the 'C' and 'H'). Assuming that all you have is a solid check engine light and no other dashboard warnings or overheating, you are not in an emergency situation. The best thing to do at this point is to locate one of the big national auto parts retailers (AutoZone, O' Reilly, Advance Auto, etc...). For no charge, most will connect a handheld computer to your vehicle and give you the error code (the reason why the check engine light came on). Once you have the details you can make a plan on what to do next (you also won't get ripped off by a dishonest mechanic lying to you about what the error code is to justify a more expensive repair).
You know why the check engine light came on, what to do next
You now know why the check engine light is on and you can go about formulating a plan to take care of the issue. You can't ignore the check engine light forever, but depending on what the problem is you may be able to drive the car for a few days without addressing it. This will give you the time to decide where you are going to get the repair done and make other arrangements for alternative transportation. Make a phone call to your mechanic and discuss the situation. It may be an extremely minor issue, such as a loose spark plug wire, a clogged air filter, etc...
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