Sounds like the control module (electronic brain) for the ABS and traction control has failed. Most of the time the traction control uses the ABS to function (it will apply brakes rapidly to limit wheelspin.) So if one fails the other is usually affected. If this is case the repair could be anywhere from a few hundered bucks to a thousand or more, it depends on the car. Also your traction control has next to nothing to do with fuel economy.
It would help if you shared what kind of car you have.