u/Far-Guarantee-5182

I have recently noticed that the speedometer on my agila sometimes doesn’t work. Most of the time I can drive away and it works fine, however sometimes it just will not move from 0, but after a few miles it fires up and works fine. Today I started up and drove off, and it wouldn’t work. after about 6 miles it started to creep up very slowly, and got stuck at around 15mph (I was doing around 40). It took a fair few miles for it to go past 15 and work correctly. Any ideas as to what this could be? Thanks!