Car was fine did an oil change vacumed some leaves and stuff under the hood. Suddenly today my speedometer is reading double the speed. Going 40 it says 80 or so. Is this a ground issue or what is going on? Any help on this would be great.

 

You haven't accidentally changed it to km/h?

 

^^
Op...you changed it to KMH when you were trying to reset the maintenance light.

 

^^^ Likely what happened but it doesn't actually double, 30MPH is 50KPH. Hopefully you got it figured out.

 

Don't feel bad. I've done the same thing and it took me a bit to figure out what I did.

 

 

Another little tid bit of information from the master to stick in the back of our brains.