Speedometer is not accurate ('23 A90)

[ChuckD]

Not sure if anyone else is having issues or have even realized there may be an issue, however, my speedometer reports my speed 2-3 MPH higher that it should. I have passed by several speed reporting signs as well as used a couple of GPS tools and they all report the same thing, my speedometer shows I am going faster than the signs and tools are reporting. This is also a very consistent over reporting. I have no mods on my car that would cause this to happen (e.g. changing rim size or tires to lower profile). Anyone else having this issue or know what could be the cause?

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[J29DB03]

It is programmed to do that. You can code it to show actual speed with BimmerCode.

 

[ChuckD]

Interesting. Do you know the BimmerCode setting that needs to be changed?

 

[zrk]

Interesting. Do you know the BimmerCode setting that needs to be changed?

In the BimmerCode User guide.

 

[Mr. Jonathan]

Personally, I decided not to code it out. Mine is a daily driver and in a few days I will forget about this thread which will likely save me from a speeding ticket. Keep at 9 (6) over the limit and your good to go.

 

[ChuckD]

Not a bad idea to just leave it. I am having a really hard time not driving it 20 (17 actual MPH) over as it is. Guess that means I also followed the break in procedures of not going over 100 MPH for the first 1200 miles since the adjusted speed would only be 99 MPH

 

[J29DB03]

I can’t remember what I decided to do. I figure maybe someday a nice person will stop me and be able to confirm if I had turned the correction off or not.

 

[FuzzyRev]

LOL, I noticed mine being a few MPH off as well.

EDIT: Is this exclusive to the manual or automatic trans? Mine's an MT, anyone have an AT with the same issue?

 

[J29DB03]

LOL, I noticed mine being a few MPH off as well.

EDIT: Is this exclusive to the manual or automatic trans? Mine's an MT, anyone have an AT with the same issue?

It’s on all. Not just the Supra, numerous automakers are doing this as well.

 

[consultadrone]

It has to do with a EU law regarding speedometers. So all European cars do this.

https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r039r1e.pdf

Or, the Cliff Notes if you prefer...

The European formula
Now it gets really crazy. The European Union requires adherence to UN ECE Regulation 39. It’s a lot of math, but the simple version is that no speedometer can read slower than the actual speed. Ever. On the high side, it’s allowed to read up to 10% above the actual speed plus four or six kilometers per hour, depending on the type of vehicle.

 

[jchadwell]

I coded mine to display the actual speed. However, from memory, the speed is only supposed to reflect .75 MPH higher than actual. It should not be 3 MPH higher.

 

[zrk]

LOL, I noticed mine being a few MPH off as well.

EDIT: Is this exclusive to the manual or automatic trans? Mine's an MT, anyone have an AT with the same issue?

It's not an issue. It's by design

 

[STV3]

I coded the fix in my car a while ago for this (don't ask me how, found it on the forum somewhere) and it's makes it better but still shows 1 - 1.5 mph slower than the speedo signs. Take that for what it's worth

 

[J29DB03]

Officer: “Do you know how fast you were going?”

Me: “Do YOU know how fast I was going… because I don’t.

 

[jchadwell]

I remembered correctly.

Speedometer Display correct Speed (not ¾ mph faster) This removes the speed adjustment so actual speed is displayed on instrument cluster. Main → Instrument Cluster (DKOMBI2) + [Expert] → 3000 ANZENGE_KONFIGURATION → BC_V_KORREKTUR → ohne_korrecktur (i.e. without correction)

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