Warning light on Dashboard on 1999 Toyota Corolla

My warning light on the top right hand side of the dashboard has come on. I checked my manual and it says that either my gas tank is empty (it isn't) or my cap is loose (it isn't) or there could be a transmission problem. I only have 40K miles on the car and have it serviced regularly. What could the problem be???

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1 answer 3 comments
Is this your check engine light? it sounds like it: http://repairpal.com/check-engine-light

This article will give you the basics on what could be wrong and what to do next.
Matte,

Thanks for the information...you were exactly right. I took my car in and it's the charcoal cannister (emissions)...I also found out that there is a design flaw in the corolla with this particular part. Thanks for your help.
I'm really glad to hear that you found a fix that wasn't too painful!!
Well, it still is an "ouch"...the total cost will be $441 to repair. The part alone is $350...I am trying to see if I can purchase the Toyota part outside of Nevada. The dealership here is a rip off. But, I am thankful that the problem was found and your information helped to find it quickly...so thanks for that.