I had this problem just after winter. As soon as I hit about 30Mph, I would get weird vibrations through the front left wheel and then ABS light would come on, traction off light would come on, and the only way to reset it was turn the car off and on again.
Well, after Pontiac quoted me $380 just for the wheel hub with integrated sensor, I heard from somewhere that these sensors can sometimes get dirty. I took my car to the local car wash, got the high pressure hose behind my wheel and blasted it for a while with soapy water. Then I took the car through my local automatic wash that does the underbody wash.
My problem went away the same day, and that was about 12,000 miles ago. I am sure I'll need a new hub soon (141k miles original) but for now its working after cleaning it.
Try that, it may buy you some time or fix it altogether.
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