engine and vsc light on 2008 Toyota 4Runner

The light comes on after a few days of getting gas, have changed the cap. I unhook pos terminal of battery to reset and works until a few days AFTER getting gas. ?

Asked by for the 2008 Toyota 4Runner
1 answer
On the left side of this post is a Q&A section. Click on the Encyclopedia, then click on the Exhaust & Emission section. Now to the right is a list and click on the EVAP section where you will find some good information on how the system functions. The EVAP system needs to be tested, and the check engine light means there should a code to help determine the proper area to be tested.