See also:

Footnotes — Maintenance Schedule Additional Required Services — Normal
a) Or every two years, whichever comes first. More frequent replacement may be needed if the vehicle is driven in areas with heavy traffic, areas with poor air quality, or areas with high dust levels. ...

Online Owner Center
GMC Owner Center (U.S.) www.gmcownercenter.com Information and services customized for your specific vehicle — all in one convenient place. • Digital owner manual, warranty information, and more ...

Footnotes — Maintenance Schedule Additional Required Services — Severe
a) Or every two years, whichever comes first. b) Check all fuel and vapor lines and hoses for proper hook-up, routing, and condition. Check that the purge valve, if the vehicle has one, works properl ...