If the cigarette lighter socket in your car is not working because you have tested it and it is faulty, then you will need to replace it. You can get it replaced by a qualified car technician, but you can also replace and install it yourself, to save some money.
1)First locate the fuse that is protecting the cigarette lighter plug you want to replace, then remove the fuse to break the circuit. Removing the fuse is vital because if you mess the wiring up, then you could cause damaged to other electrical things in your car. To locate the fuse that protects the cigarette lighter, check in the user handbook for your car's make and model.
2)You will now have to remove the faulty cigarette lighter socket, so remove it from the car's dashboard, this is by inserting a flat head screwdriver into the sides of the cig socket. It should pry out, if not, you will need to release the metal clips that hold it in place.
3)Once removed, you will see two wires that are connected to it, that use spade connectors, remove them both, so they are disconnected.
4)Now get the replacement cigarette lighter and connect the spade connectors onto the spades on the rear of it, matching the red and black colours.
5)Once you have connected the wires, you fit it in, this is by pushing the outer case into the dash hole.
6)Once pushed in all the way, the two metal clips will lock the cigarette lighter socket in place, so it can't move.
7)Now all is left is to replace the fuse you removed and your done:)