Under the Service functions of the SDD 131 is Engine Emission Control- Evap system Leak Check.

It indicates it wants to close for 30 minutes. My question is what is this actually for/do and is it intended for getting the Evap ODBII showing complete or for something else entirely other than check for Evap leaks?

Thanks

Tom in Dallas/Plano

05 S-Type 3.0 122k