Thought I'd pass this along for anyone wanting to correct their speedometer indications.

Previously I used NCS Expert to modify the KOMBI module with the BC_DIGITAL_V_KORREKTUR setting posted elsewhere. I also modified the analog corrector settings with less than optimal results. The digital speedo read correctly, however the analog never changed and when I would use the cruise control the numbers on the cruise setting never matched the speedo.

I had stopped into a different BMW service shop than I usually visit and asked about having it changed. I was informed mine wasn't far enough out for them to correct this (4 mph). Thank you once again BMW. (Note to Admin: We need a middle finger smilie icon)

Further digging revealed the following codes buried in the KOMBI module.
K_ZAHL_TACHO - Impulses per kilometer for speedometer
values wert 1 to 3
K_ZAHL_TACHO_KOMPL - Impulses per kilometer for speedometer (Complimentary)
values wert 1 to 3
K_ZAHL_WEG - Impulses per kilometer for odometer
values wert 1 to 2
K_ZAHL_WEG_KOMPL - Impulses per kilometer for odometer (Complimentary)
values wert 1 to 2

I altered the first two settings to a value of 2 and low and behold both of my speedometers now read within 1 mph of my GPS speed app on a straight stretch of road.

Happy Motoring

 

This is some good info! that speedo difference really drives me nuts! I just always mentally figure in 8%-10% difference: 55mph speedo= 60mph actual... 70mph Speedo= 64mph actual....

 

i changed tire size from 225/45R18 to 225/50R18 (25.9 inch OD to 26.9 inch OD) and both speedos and cruise control are now spot on compared to my aviation GPS that reads speed in .1 MPH increments

car was originally 1.9 MPH slower than GPS actual

with my 205/70R16 winter tires (27.3 inch OD), i read .6 MPH under actual GPS speed

 

I'm kind of confused, do you still have to do the BC_DIGITAL_V_KORREKTUR change or just the two new ones that you found? I'm thinking that the original one fixes the digital and the two new ones fix the analog.

What do you think the other two (K_ZAHL_WEG and K_ZAHL_WEG_KOMPL ) do?

 

Nope, the old DIGITAL setting is no longer needed. The two TACHO entries will correct both the analog and digital speedometers. In addition when you set your cruise control, the speed setting will now match both speedometers.

The WEG settings should only be changed if your odometer is off as well.

 

Why don't you make this thread a sticky so some rookie doesn't wander in to the forum and start ANOTHER 'why is my speedo off' thread without searching first.
PS: Only reason I opened this thread was to see did that very thing happen again.

 

Hello all,

Be advised that you can add new parameters with whatever needed values (using NCS Dummy) to these two sections - allowing more or less exact adjustment of the speedometer reading.

I changed from value_03 to value_02 to get my MINI (using stock tire size) to within about 0.5mph of actual.

Then I changed from stock tire size to 205/50-16 and I was back to being about 1.5 - 2mph off.

I compared the OEM values for value_03 and value_02 and noted the speed display change then calculated new values that would remove the error brought in by the new tire size.

It worked, I've got new-sized tires and an accurate speedo.