New speedo sensor - reading far out

Hello,

I have a Clio II (2001),

The speed was dropping out intermittently on the dial, until one point it was off permanently.



Assumption was speed sensor was knackered, tried to clean but did not work.

I replaced it with a new one off ebay,



The speed appears on the dial now but it is far out from the actual speed.

I got a friend to drive beside me at 40mph but my dial was reading 30mph and tried again with them driving 60mph beside me and mine was reading 45mph (worth to mention it actually feels like 60mph as well).



Any ideas what the problem could be?

Thanks,