Reasons Why Your Check Engine Light May Be On
If the Check Engine Light comes on while you’re driving, it can be unnerving. Don’t panic, though.
Take a moment to see if the car is driving any differently than normal. Is it bucking? Surging? Are there any unusual sounds? If nothing seems out of the ordinary, you can continue driving the car. It could be anything from a failed oxygen sensor to a bad MAF sensor. It could also mean that your catalytic converter is going out.
A loose gas cap could also be the reason!
This is the easiest and most common occurrence in many vehicles. If the gas cap is not tight enough, your check engine light may turn on. Many people don't know this, but a loose, cracked, or faulty gas cap can cause fuel to evaporate, thus causing this issue.
So pull over when it’s safe and make sure your gas cap is on tight. Turn the cap until it clicks a couple of times and you should be okay. It may take a few miles of driving for the light to go off. Also, driving without a gas cap or a loose gas cap will not cause you to lose fuel. There is a flapper valve built into your car, and it will stop fuel from flowing out of your tank. If the light continues to stay on there could be another issue.
Aside from a loose gas cap, all other reasons for your check engine light coming can be much more complicated to diagnose (and likely not something you can fix on the side of the road).
Triggers can include everything from a damaged vacuum hose or ignition coil(s) to a failing catalytic converter to worn out spark plugs (to name a few).
No idea what any of that means? That’s OK — most people don’t. Most modern cars have an on-board diagnostic system that provides a code identifying the specific issue at hand. If you take your car to a certified technician they can diagnose what the code means so you can act accordingly. This code is only the starting point and gives the technician a place to start looking into that specific system. So when you see that light flickering in the corner of your dash, know that while you will need to see a mechanic in the near future, there’s absolutely no need to panic. It’s OK to keep going, just make sure you have it checked out as soon as you can.