Most Common Check Engine Issues
Check engine lights come on for a myriad of reasons. Maybe your car is low on coolant or you forgot to put your gas cap back on the last time you were at the gas station. Out of the thousands of endless possibilities, the most common are below. Most likely at least one is related to what you are searching for.
One of the most frequent reasons why your check engine light comes on is because your car is due for a tune up. The reason this is the most common check engine light problem is because the emissions system in your car usually is the first system to fail in the life cycle of your vehicle. If the check engine light comes on and stays on most likely it is an issue with a bad spark plug or spark plug wire or simply the cap and rotor that distributes the spark in your car is failing. A major indicator that you are in need of a tune up is if your car starts to hesitate when stepping on the gas pedal. When in doubt get a tune up first before you start throwing parts at the car.
Faulty gas caps, missing gas caps and improperly put on gas caps will definitely trigger your check engine light to come on. The reason being is because the oxygen sensor in the engine will detect a drop in pressure due to imbalance oxygen to fuel ratio. Incredibly this is probably the second leading reason why the check engine light comes on. If you've done a tune up and the check engine light is still there. I would definitely check the cap and seal on your gas cap.
Though not as common as the first two the exhaust gas recirculation valve at times can get clogged with dirt and trigger the check engine light to come back on. The main indicator that your EGR valve is going bad is if you detect a strong odor of gasoline when you operate your vehicle.
If you have done all three of the above things and nothing has worked, all hope is not lost you still have options to figuring out what the heck is tripping the check engine light.
Every local auto parts store will carry a basic OBD (onboard diagnostic) code reader that will pull the error code for you. Generally the OBD reader will come with a book that will allow you to look up what the code means. This at least gives you a direction on where to start troubleshooting in addition most OBD code readers will allow you to clear the check engine light, however be warned a cleared light does not mean it won't come back on again if you don't take care of the problem.
Worse case scenario your OBD code reader doesn't give you enough information you'll have to take it to a shop where they have the professional grade code reader that allows them to drill down even further to figure out what the problem is with the check engine light.