Q: Gascap light is on, how can I fix it?

The cap, or cap seal, is defective and/or there is a leak/malfunction in the EVAP (vapor side) of the fuel system. You should first look for a leak (to avoid needlessly buying a new cap), however, that inspection might require a "smoke machine". What I would suggest is you request a gas cap/seal inspection and in the course of that if a smoke machine diagnostic is needed the responding mechanic can deal with that. If you do end up needing a new cap, I recommend buying the OEM cap from the dealer. Some aftermarket caps are just simply not compatible with OEM designs and will not be reliable. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.