This says yes water heater.

https://www.ajmadison.com/cgi-bin/ajmadison/EFLS517SIW.html

@Tracey_OH

Yes it does have an internal heater.

If any washer has a Sanitary (Sanitize) cycle by way of heating the water to a temperature over 150 then it has an internal heater. For the most part if it offers a Steam cycle or option usually (not always) it's produced by the heating element.

Sorry you had to deal with an uneducated representative from Electrolux (they must have missed that day of product education).

A cycle marked "Sanitary" does not guarantee a heater. Specs for the machine -- available on the website -- must state "onboard heater."

There is no standard for sanitary. It's a must-do to check for the heater and to ask what the hottest temperature the machine will generate. The manufacturer should be able to provide this information.

Here is an article that explains. It's not easy to understand.

http://manuals.electroluxappliances.com/prodinfo_pdf/Specsheets/EFLS517S_0317_EN.pdf 

Via Electrolux website it states the 517 has the heater.

Thank you all for the help. They sure don't make it easy to find this information! The Home Depot website has a search function that allows you to search by feature. If you search for Electrolux washers with an internal heater, the only model that comes up is the Electrolux 250 2.4 cubic ft. so I was starting to doubt myself. Thanks again!