Since you seem to be the Ford guru here, I hope you can give me some guidance: 2005 Ford Explorer, 2WD XLT sport, 4.0L V6. Since yesterday, every time I start the engine, the information panel shows “advtrac off” (it isn’t) then changes to “check advtrac” and the little swervy warning dash light stays on steady. I checked the owner’s manual and it just says have it checked. A google search indicates that it is most likely a bad rear wheel sensor. Is there something simple that a regular person can do to check/fix the situation or is this something a shop or dealer should take care of?