VW Transporter T6.1 2021 Wheel size coding changes issue

[AudiGit]

OK, makes sense. So I should just move to the next variant (3) and see if it accepts that?

Yip, one by one to check which gets accepted. I know you’re aware but just to mention that it can’t be reverted, for the moment.

 

[JimmyAK]

A final(?) update. So I got brave (or foolish) one evening and decided to try it regardless and finally... success! So thought I'd come back here and post my results in the hope it helps somebody else out.

So as a reminder, my conversion was based on a 22-plate T6.1 Startline (T30 150 DSG) with optional business pack. So the OEM wheels were 16 inch steels with 205/65 R16 tyres. As posted previously, the K-number (IDE00842) doesn't seem to exist on the T6.1 and instead there's just two different IDE00845 values, one for trip distance (2066mm) and one for speed (2149mm).

When I looked at the long coding helper I could see my wheel circumference was set to variant 1 - makes sense given the 16" steels are probably the smallest wheels fitted to the T6.1 out of the factory.

So with my 275/40/20's fitted, the speedo is reading ~4mph low at 70mph (speedo = 66mph, measured GPS speed = 70mph) which is pretty much in line with what willtheyfit.com tells me.

So I know from this thread that changing the wheel variant on the new T6.1 platform is a one-way street. i.e. you can increase the variant but not go backwards. So my approach was to increment the variant one step at a time, hoping they scaled in a relatively linear fashion.

Step 1 - set to variant 2. Coding was rejected (Request out of range).

Step 2 - set to variant 3. This time coding was accepted, and my IDE00845 values were increased to 2111mm / 2195mm respectively.

A quick test drive confirmed my speedo error was reduced to about 2-3 mph.

Step 4 - set to variant 4. Coding was rejected (Request out of range).

Step 5 - set to variant 5. Coding was rejected (Request out of range).

Step 6 - set to variant 6. Coding was accepted, and my IDE00845 values were increased to 2195mm / 2293 mm.

Another test drive and now my speedo is pretty much bang on. At this stage I was very happy to call it quits. Whilst I could have tweaked it higher so that the speedo reads a little higher than actual (as is common practise), I wasn't willing to risk a large leap in circumference knowing that I couldn't revert back. Incidentally I did try going backwards just to verify, and can confirm I got 'Coding Rejected Error 22' which prevented me from doing so.

Thanks to everyone who chipped in with advice, particularly 'AudiGit' who gave me sufficient confidence to go for it!

I hope this helps out anyone looking to do a similar tweak.

 

[DV52]

@JimmyAK : thanks for taking the time to share your findings. I'm very interested in your observations and whilst there is much in your written words - access to the pictures would add an extra dimension to my (our?) understanding.

I'm not sure how you see this webpage on your laptop/PC, but if you log-out of the forum and come back to this thread, you should see that your pictures are not accessible.

The instructions for posting pictures on the forum can be accessed by clicking on "how to" at the top of this webpage and selecting the appropriate option.

Don

 

[Uwe]

if you log-out of the forum and come back to this thread, you should see that your pictures are not accessible.

He's trying to link pictures that he uploaded to another forum. They probably load for him because he's logged into that forum himself, but not for us because we're not.

[IMG alt="1654512269845.png"]https://www.t6forum.com/attachments/1654512269845-png.159451/[/IMG]

-Uwe-

 

[JimmyAK]

He's trying to link pictures that he uploaded to another forum. They probably load for him because he's logged into that forum himself, but not for us because we're not.



-Uwe-

Apologies, that's exactly what I did. I didn't realise the images wouldn't appear for non-logged in users. Hopefully all fixed now! Note to self - RTFM.