2. Check the air filter. A dirty air filter can restrict airflow to the engine, which can cause the check engine light to come on. Replace the air filter if it is dirty.
3. Check the spark plugs. Worn-out spark plugs can cause the check engine light to come on. Replace the spark plugs if they are worn out.
4. Check the oxygen sensor. A faulty oxygen sensor can cause the check engine light to come on. Replace the oxygen sensor if it is faulty.
5. Check the catalytic converter. A clogged catalytic converter can cause the check engine light to come on. Replace the catalytic converter if it is clogged.
If the check engine light is still on after you have checked all of these things, you will need to take your car to a mechanic to have it diagnosed.
