Hi.

I have a Fabia Combi 1.4 MPI. Basically, my problem is that the speedometer lies too much. For example - There's 90 km/h limit and if I try to stick to that I would have to go atleast 100. I checked my readings with a GPS system and it confirms the 10 km/h mis-read. Even worse, when I'd like to go 110 km/h, I'd have to push to a whopping 127 km/h.

I know that all speedometers lie about 5 km/h but that is just ridiculous.. I decided that I should check if my tyres are too small - they're 185/60/R14 and that's exactly a measure that is shown on fuel filler cap. So the tyres are not the culprit.

The over-reading is not that dramatic with winter tyres which are 165/65/R14 but it still occurs a bit.

Any ideas?

I find my odometer underreads by about 7mph. If i stick the cruise control on at 60mph and look at the onboard diagnostic in the climatronic (funtion 19 - 2) i get a reading of 53 mph.

My general opinion is to stick with the digital reading as this is directly from the computer and the analog odometer readout could be out of calibration.

I'l take a piccy sometime and show you.

I find my odometer underreads by about 7mph. If i stick the cruise control on at 60mph and look at the onboard diagnostic in the climatronic (funtion 19 - 2) i get a reading of 53 mph.

I don't think the 7mph will be constant though.

Rather the mis-read is a fixed percentage of the spped you are doing?

Assuming the cars speed sensor isn't goosed, a dealer can adjust speedo calibration with the VAG box of tricks.

Mine is the same, seems to be about 6 mph out at 70 mph

I find my odometer underreads by about 7mph. If i stick the cruise control on at 60mph and look at the onboard diagnostic in the climatronic (funtion 19 - 2) i get a reading of 53 mph.

Underreads? Isn't it a legal requirement that they don't do that?

Back on topic, mine is ~+10% out, but I believe as said, they can be calibrated - something I would rather not do as I am used to it being too opmisitic.

If I compare my speedo reading and the reading on my dads GPS Sat Nav on his phone, then my speedo under reads by a few percent (less than 10%) I have also found out my dads Subaru does the same, but I won't tell you how much by and what speeds it was. (....70 mph, of course, officer) but again it was less then 10% under.

Some people say you are allowed to be up to 10% over if you are court speeding to compensate for the speedo being inaccurate.

Edited 24 June, 200917 yr by Jim H

I decided that I'll try bigger tyres. Tomorrow I'll go and pick them up and give them a go. Old ones are pretty worn anyways...