* Oxygen Sensor (O2 Sensor) Issues: These sensors monitor the exhaust gases to help the engine run efficiently. A failing O2 sensor is a very common cause of a check engine light, leading to poor fuel economy and potentially higher emissions.
* Mass Airflow Sensor (MAF) Problems: The MAF sensor measures the amount of air entering the engine. A dirty or malfunctioning MAF sensor can cause the engine to run rich or lean, leading to a check engine light and potentially poor performance.
* Catalytic Converter Failure: This component reduces harmful emissions. A failing catalytic converter can be expensive to replace, and often manifests with a check engine light and reduced engine performance.
* Ignition System Problems: Issues with spark plugs, ignition wires, or the ignition coil can cause misfires, leading to the check engine light.
* PCV Valve Problems: The Positive Crankcase Ventilation (PCV) valve helps remove harmful gases from the engine. A clogged or faulty PCV valve can cause a build-up of pressure and trigger the light.
* Evaporative Emission System (EVAP) Leak: This system prevents fuel vapors from escaping. A leak in the system (e.g., a loose gas cap) can trigger the light. This is often a relatively easy fix, starting with checking the gas cap.
* Throttle Position Sensor (TPS) Issues: The TPS tells the engine control module (ECM) the position of the throttle. A faulty sensor can cause erratic engine behavior and trigger the light.
* Crankshaft Position Sensor (CKP) Problems: This sensor tells the ECM the position of the crankshaft. A faulty CKP sensor can prevent the engine from starting or running smoothly.
Important Note: The check engine light itself doesn't tell you *what* is wrong. You need to use an OBD-II scanner to retrieve the Diagnostic Trouble Codes (DTCs). These codes will pinpoint the likely source of the problem, allowing you or a mechanic to diagnose and repair it efficiently. Ignoring the light could lead to more serious and expensive problems down the line.
