2003 GMC Envoy XL Service Engine Soon Light on steady

What does this mean? It came on steady over the summer on a long trip from PA to FL but once we changed gas to premium it went off. We just recently took the car on a 2 hour trip and halfway during the trip it came on again. I haven’t tried premium gas this time but after researching online I’ve been reading about gas tank or filler neck issues. Is there a recall on this? I’ve seen places that say there is and others that say there isn’t. Where can I get this Service Engine Soon light checked for free and should I just try the premium gas first? Thanks.

Parts store like Autozone can retreive codes. When they’re retreived post back here with the codes, not the explanation of code, something like P0171 or something along those lines and we might be able to help.

There may be two lights, depending on the car.  One indicates a problem that needs to be addressed.  This is the CEL (Check Engine Lamp)  The other is the SESL (Service Engine Soon Light)  It would appear yours is the service light.  That means you may be due for an oil change, new plugs etc.  These are scheduled maintenance items and the light is just a reminder. 

The CEL is more serious and should be addressed ASAP.  Letting this one go could cause a safety issue or cause damage.  

Looking in your owner's manual (should be in the glove box or in a special place at home) will tell you exactly what it means on your car. 

Neither of these lights are going to be turned off by using premium fuel unless your GMC  [b] requires[/b] premium fuel.  Using higher octane fuel that recommended in the owner's manual or a sticker on your car is a waste of money.   [b] premium fuel is not BETTER than regular[/b] and it does not have more power than regular.  It just burns slower and many high performance engines are designed to use it.  

As Pete wrote, if it is a CEL then, That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.