The engine management system has detected an anomoly which has triggered the "SES" light to come on. In many cases this is not a major issue and can easily be resolved. In fact, a common cause is the gas cap not being on tight, so you may want to check that. Either way, it does need to be checked out in the near future to find out for sure what it is that triggered it.
This is NOT the same as the service interval lights, they are completely independent
The dealer can hook the vehicle up to their computers to find out the cause from the fault code that is stored in the system. Alternately, you can stop by any independent mechanic and they can hook up a code reader to the OBD-II port and tell you what the fault codes are. Myself, I have an Actron OBD-II scanner so that I can pull (and reset) the codes myself.
