Calibrating the speedometer?

[FWP!]

For months I've been wanting to figure out if the speedometer can be calibrated. Mine, for example, will show 80 mph, but my GPS, my phone, and my radar detector all show exactly 75 mph. So the speedo is "optimistic" by about 5mph.

Is there a way to go in via vag com or something to fix this? My speedometer in my girlfriend's S4 is dead on accurate.

[993140]

Don't know if it can be calibrated, but mine's the same and pretty much all cars I've owned before were exactly like that. My daily driver 2014 B8 S4 is dead on as is yours, but this is my first ever car with such an accurate speedo.

[FWP!]

Yea, seems to be a fairly common issue - http://www.audizine.com/forum/showth...te+speedometer

Well, I just take that percentage difference and apply it to the mileage my odometer is showing, haha.

And yea, the S4's is perfect, all the way up past 120mph. The RS4's gets worse and worse. There's gotta be an option somewhere in vag com to make this adjustment..

[PetrolDave]

In Europe it's a legal requirement for the speedo to over-read by up to 10%, so most EU manufacturers setup their speedos to over-read by 5% to make allowance for tolerances, tyre wear, etc.

[FWP!]

But the S4 is dead on..

[WinterRunner]

Use the digital speedo in your navigation, its the most accurate

[gesTTalt]

You can't via vag. I swapped to 265/35-19 tires and now my speedo is pretty close to my gps and the RSNE speed. I also used vag to entire a new tire size, but system will calibrate it over time on its own.

[PetrolDave]

But the S4 is dead on..

How worn are the tyres? As the tyres wear and the rolling radius reduces the speedo becomes more accurate.

[FWP!]

Brand new PSS's

[FWP!]

Use the digital speedo in your navigation, its the most accurate

Wat?

I went into engineering mode, saw that that speed is dead on accurate, but I want my speedometer in the instrument cluster to be accurate too. It's exactly 6 MPH higher than actual speed at 80 MPH (actually going 74 MPH).

[PetrolDave]

I want my speedometer in the instrument cluster to be accurate too. It's exactly 6 MPH higher than actual speed at 80 MPH (actually going 74 MPH).

As already said by others there is no VCDS method to change the speedo calibration, you'll either have to have your speedo professionally recalibrated or live with the error.

[FWP!]

Well, it sounds like you can modify the tire diameter via vag com so I may try that.

[PetrolDave]

Well, it sounds like you can modify the tire diameter via vag com so I may try that.

AFAIK that only affects how rapidly the RNS-E learns the distance calibration factor it uses and has no effect on the instruments.

AFAIK there's nothing on the Ross-Tech wiki about tyre calibration on address 17 (instruments), only adaptation channel 1 on address 37 (navigation).

[Flying Tomatoes]

AFAIK that only affects how rapidly the RNS-E learns the distance calibration factor it uses and has no effect on the instruments.

AFAIK there's nothing on the Ross-Tech wiki about tyre calibration on address 17 (instruments), only adaptation channel 1 on address 37 (navigation).

That's what I've been told as well. Can't confirm either way though.

[B-Time]

I recently went with one size wider tire and my speedo is now accurate. First time in 14 years of driving an Audi.

[beamon]

No wonder the car seems so fast...when in reality it isn't quite as fast

[rbbny]

Well I was going 80 and change according to the speedo and got ticketed for 82.

[PetrolDave]

I recently went with one size wider tire and my speedo is now accurate. First time in 14 years of driving an Audi.

If you've kept the same profile of tyre then that's increased the rolling radius = more distance per turn of the wheels = actual speed increased compared to indicated speed (which just counts turns of the wheels in a given time).

[RAudi Driver]

What does this do to the mileage on the odo.

Back when I first got my car, I tested it with mile markers on the way to Las Vegas. For ever mile marker I passed, the odo increased by 1.2 miles.