If there is an Autozone parts store around, they will read the code
for free.  Maybe some other parts places in your area will read them
for free too.  Ask around.  The code won't necessarily tell you what's
wrong.  It will tell you what parameter being monitored has gone out
of specification.  You need to understand what the parameter is and
what the monitoring logic is to determine what might be wrong.
Sometimes that's very straightforward.  Sometimes it's not.  Good
luck.  Al