Well I found this in the owner's manual pdf version online
https://cdn.dealereprocess.org/cdn/brochures/chevrolet/2016-sparkev.pdf
last page says "charging system" and many other components are covered too.
California has a longer warranty than the federal requirement for BEV drivetrain/battery, 10 years vs 8 years.
The dealer reports I need a new onboard charger. After many months they got one in stock. But now they say its not under warranty.
I can't find the text of the California...