My ford focus has just had a new coil pack fitted, but the engine management light is still on?

The garage has said that it could be the auto sensor… What is this? Will it be an expensive fix? Advice please!

Drive it for a week and it should turn off automatically. If not then go back to the shop.

On most Ford models the codes need to be erased after the repair to turn the warning light off. That should have been done when the repair was made. Some warnings will cancel themselves after a certain number of cold starts however.