To check the balance of a Mobil gas card, navigate to the ExxonMobil website, Exxon.com, and use the online balance checking system the company provides. The Gift Cards page on the ExxonMobil website includes a link to the online balance checking system.
To get to the Gift Cards page from the ExxonMobil home page, choose the Gas Cards & Payment menu category and the Gift Cards subcategory. After navigating to the gift card page on the ExxonMobil website, click on the Check Your Gift Card Balance Here link. Choose the View Card Balance menu option. Enter the 19-digit gift-card number and the six-character security code. Click submit to view the balance on the gift card.
An ExxonMobil toll-free number that card holders can call to check their balance is also available on the back of the gift card. As of 2015, ExxonMobil offers gift cards in denominations of $10, $25, $50 and $100.