The check engine light comes(CEL) on when the computer detects a fault in an engine driveability component, transmission, or emissions system. There are literally dozens of components or causes that can make the check engine light to come on, ranging from an engine mis-fire, vacuum leak, transmission solenoid or other related component. To find out what is setting the CEL, a diagnostic scanner has to be hooked up to the vehicle's computer in order to read the computer for DTCs (diagnostic Trouble Codes). Autozone, among other auto parts stores, will do this for free. Once the DTCs are read, they will give you the code number and what it relates to. Sometimes it is a straightforward parts relplacement, other times it requires following a flowchart to further diagnose and isolate problem. At that point you can decide whether to repair yourself or have a shop do the repair. Once you have the code numbers, you can re-open this question and I can help you in diagnosing and repairing the vehicle correctly.
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