Speedo reading higher than actual speed

[tundrarocks]

Sister in law has just bought a 2004 arosa and has noticed the speedo is reading 7mph faster than she is going. Ive read that can be a loose earth wire but ivenot been able to locate it. Can anyone give me a better idea where it's located or photos ? Am I looking for a single brown wire attached to the car body ?

 

[CatB1]

At what speed is it reading 7mph faster, was it checked with GPS, has it got the original size wheels/tyres?


Pete

 

[tundrarocks]

It seems to be out all the way through the range. She has been using at sat nav to make sure she is sticking to the speed limits as she has just past her test. Its the same when you go through those speed check signs the speeds are out by a good margin

 

[tundrarocks]

Oh and it's totally standard wheels etc

 

[Dan1720v]

New tyres?

 

[Slimy]

Speedo's always read higher than actual speed. They're allowed to read up to 10% more than actual speed but not lower. For example, when my speedo reads 75, my actual speed is 69.

Most manufacturers will set it so it reads higher, but things like sat nav and traffic signs are a bit more accurate.

 

[tundrarocks]

It must be a seat thing because my Leon fr is about 5mph less than my actual speed according to sat nav and road side speed signals. I've never noticed it out by so much on other vag cars I e owned.

 

[Slimy]

It must be a seat thing because my Leon fr is about 5mph less than my actual speed according to sat nav and road side speed signals. I've never noticed it out by so much on other vag cars I e owned.

So when your speedo reads 30 you're actually doing 35? That's actually your Leon at fault rather than her Arosa! I'm guessing you're very careful when you pass speed cameras?

Other cars that I've driven/maintained have ranged between 2% and 7% below actual. I don't think I've ever had a car that was spot on?

 

[NickCupraR]

Had a skoda fabia that was about 10% too high. My Ibiza was about 4% out. It therefore makes the MPG over as well and more importantly the mileage will be higher too.

 

[tundrarocks]

If my speedo reads 30 I'm actually doing 25mph. That's going of sat nav and those speed check signs put side schools. My sisters arosa is the other way around and reads 7mph slower than she is going!
Everything is standard on both our cars.