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Gas cap and message on dashboard

My gas cap says that when I put it on,I am supposed to turn it 3 clicks. My dashboard message says that my gas cap is loose. I check it about a dozen times but to no avail. My service engine light also comes on. The manual says that there might be water in my gas and to use a premium gas. I do this and it seems to work for a day or two and then goes back to the message again. I hope someone can help me. I think my sensor will burn out because my message is on all the time. Thanks!

How old is it? You could buy a new gas cap at the auto parts store, see if that fixes it. At that time also have them read the codes on your car’s computer, let us know what they are.

Some years of Buick have a separate circuit that activates if there is a vapor leak in the evaporative emissions system. The most likely candidate is a missing or loose gas cap so the “check gas cap” light illuminates. However, anything that causes the vapor pressure in the tank to leak will also turn that light on and set the CEL.

As Texases submitted install a new gas cap. If the “check gas cap” light comes on again, you will have to take it to a mechanic to have the tank vapor recovery system diagnosed. Depending on how old this Buick is it could be a degraded hose or other seal. There are so many places the vapor pressure can leak from that throwing parts at the problem is not cost effective.

Hope this helps.

Yes, click it a few times. However I suspect that you had a CEL (Check Engine Light) and someone told you that it was the gas cap. It might be, but then it might not. The light does not say gas cap. There is a code that indicates there is a leak in the fuel vent system. That often means someone did not put the gas cap on tight. Cheap to try and hope that was it. However there are other possibilities that the same code may result from. It would be a good start by telling us a little more.

Make, Model, Year and Mileage is your car? Did someone actually see the light and check in a manual as to what it meant? There should have been a code like [P1234] find out what code you had and let us know in a reply to this thread.

[b] The manual says that there might be water in my gas and to use a premium gas.[/b] 

Really. How would it guess you might have water in the gas?

Unless your Owner’s Manual says you need or should use premium, there is absolutely nothing to gain and it will cost you more. I might be talked into believing your car really runs well after you fill it up, but I would be more inclined to believe it is doing so because there is a problem with the in tank fuel pump and the filter/screen that is in the tank. Premium will never fix that. If it really is the problem then premium gas will do nothing, You will need to have the tank cleaned.

Now if you have a Service Soon light on, then you need to have your car serviced. Maybe oil change, filters etc. You need to see your owner’s manual for more specific information.

Thanks for the replys guys.
My car is a 2000 Buick LeSabre. I knew it was the gas cap because the message on the dashboard said it was.
I will try the new gas cap and see what happens. When I go to the auto part store and ask them for the codes, where do they read them?
Thanks, again, I appreciate it!