If your vehicle is showing check engine light is illuminated, here are the most likely causes and the parts you'll need to fix each one.
A loose, damaged, or missing gas cap allows fuel vapors to escape, triggering an EVAP system leak code. This is extremely common right after refueling.
Oxygen sensors degrade over time from exhaust heat and carbon buildup, causing incorrect fuel mixtures and triggering emissions codes.
Worn spark plugs or failing ignition coils cause the engine to misfire. This often triggers a flashing check engine light and causes the engine to run rough or shake.
The MAF sensor measures air entering the engine. It can get dirty over time, or it is frequently left unplugged by mistake after checking or replacing the engine air filter.
Valves that route fuel vapors into the engine to be burned can stick open or closed, causing EVAP codes even if the gas cap is tight.
The catalytic converter cleans exhaust gases. If it fails or becomes clogged (often due to ignoring misfires or burning oil), it triggers an efficiency code.
If the thermostat fails in the open position, the engine will not reach its proper operating temperature fast enough, triggering a specific code (like P0128).
Low or dirty engine oil can clog VVT solenoids, or the solenoids themselves can fail electrically, causing engine timing codes.
Cracked hoses or a stuck PCV valve allow unmetered air into the engine, causing it to run lean and triggering a light.
Rarely, the computer itself fails, suffers water damage, or has an internal short, causing erratic codes and drivability issues.