po440

you can turn the light off yourself by discontecting the battery cables & touching them together. otherwise it will wait until you have completed a drive cylce where it didn't detect a leak. it may take quite awhile for this to happen. some auto parts stores will scan or clear codes for free.

I have been in the automotive reapir business for a while, and found that only about 20% of the p0440 codes, in my area, are due to a faulty fuel cap. You may need to get more involved in the EVAP system.