Strange one

[birdie2626]

Hi guys, i need some help
Ive owned my clio 172 51 plate phase 2 for a month and the speedo has started to go crazy.
This only happens when i have my lights on though. Its adding miles onto my car when I'm stationery as its jumping around between 0 and 160. When my lights are off all is fine.
My odometer also resets itself everytime i start the car and i changed the battery on Sunday hoping it would rectify this.
Are these linked, Any help much appreciated!

 

[daveypower]

The speedo sensor is on your gearbox, i dont know why i only happens when your lights is on though, theres a wiring fault somewhere, anyway take your sensor out and clean it, check connections etc, if that dosent fix it, unplug it so your speedo wont work atol, and at least your miles wont be going up until you fix it.