This problem is most commonly caused by overloading the cig-lighter/ accessory power power socket with a mobile phone charger etc.
The problem is the fuse is underrated for power applications such as sat navs etc
How to fix :
Precautions Turn ignition off and make sure you have the keys in your pocket, or wind down a window, it can lock the doors after a short delay if you mistakenly unplug the wrong fuse and lock you out !!.
Look in the fuse box under the steering column, fuses are in two rows
bottom row 3rd fuse from the right
usually a yellow 20 amp fuse, take it out and replace with the spare 30 amp one.
Do not be confused if the fuse looks ok, it is common to have a burning mark on the leg which breaks the circuit yet the fuse looks intact.
This will restore the power to the speedo and cig socket.
google tags :
Vauxhall corsa 12v 1.0 speedometer fault, speedo fault, speedo not working
Mark Readman
May 2008