Alternately, it can be a loose battery cable such as this one example:If you're getting random "Service XXXX" messages, you have a dead 12V battery. Either something drained the battery, or the battery itself is defective.
With all the computers in the Volt, it can do some very strange things if there is unstable 12V power.Some intermittent electrical problems have cropped up on SOME Gen2 Volts.
It appears the poorly aligned 12V battery cable connection at the back of the underhood fuseblock MAY account for some of those
As such GM has decided to issue a Service Update Campaign # 16017 -Battery Cable Misaligned
specifically for units in currently dealer inventory.
But it sure wouldn't hurt to take a look at YOUR Volt. (see photos below)
If the connection is misaligned- see your dealer!!