Speedometer Error??

NSTDI · Oct 1, 2012

I checked mine today, at 106KPH on the speedo, my Garmin said 100KPH. It seems pretty consistent at the 6KPH error at 90, 100, 110, and 120KPH.

Anyone else check their speedometer?

I also checked the odometer, it seemed OK. I measured it over a 40 KM stretch, using the KM markers at roadside.

Any idea how the speedo can be recalibrated?

Don

Nebelwerfer · Oct 1, 2012

This is normal. Most cars I've driven in Germany have the same error and I've been told by locals there that its to help reduce accidents.

I haven't seen any threads here saying it can be sorted out. It is annoying but you extend your MPG if you learn to live with it.

Regards

NSTDI · Oct 2, 2012

My 2003 Passat was out maybe 1 or 2 KPH slow, which is not all that significant. 6 is a lot- driving 100KPH around here, when it is really 94KPH, will cause long lineups on a 2 lane highway. I'd rather choose my own accurate speed.

How fast do you drive to average 7L/110?

Don

IXLR8 · Oct 2, 2012

This has been well documented here and on the B7 thread in V-tex. Both the speedo and the odo read low compared to actual. Hmmm.. but you are saying the opposite. Mine reads 75mph, Garmin says 78mph... officer issuing ticket said 78mph. Either way, using VCDS, in Instrument Adaption, you can select different vehicles which will recalibrate them to read more accurately. If you want the MFI MPG readout to be correct, then this needs to be done before you recalibrate the MFI readout.

shoremnj · Oct 2, 2012

At 70 MPH on dash my GPS reads 73MPH and so on. Always less than actual speed.

WutGas? · Oct 2, 2012

Not the NMS, but my Jetta reads about 1 mph low. 61 on Garmin - 60 on speedo.

VeeDubTDI · Oct 2, 2012

Our cruise control displays 1 mph slow and the gauge is about dead on. When we first got the car there was more of an error. I've never had a self-healing car before... pretty cool!

TurboDieselPoint · Oct 2, 2012

VeeDubTDI said:
Our cruise control displays 1 mph slow and the gauge is about dead on. When we first got the car there was more of an error. I've never had a self-healing car before... pretty cool!

Your tires have shrunk!

GeekDrew · Oct 3, 2012

VeeDubTDI said:
Our cruise control displays 1 mph slow and the gauge is about dead on. When we first got the car there was more of an error. I've never had a self-healing car before... pretty cool!

How about the SGII?

VeeDubTDI · Oct 4, 2012

SGII is adjustable - not sure what the correction factor is at the moment. I'll check later when I go out to run errands.

NSTDI · Oct 4, 2012

What is SGII?

Don

VeeDubTDI · Oct 4, 2012

www.scangauge.com

Im_infected_with_theVWbug · Oct 4, 2012

Just my recordings:
1997 Jetta GLS 2.0L Dash Speed 80mph/ Garmin or TomTom 79mph
2000 Passat GLS 1.8t Dash Speed 80mph/ Garmin or TomTom 76mph
2002 Jetta TDI 1.9L Dash Speed 80mph/ Garmin or TomTom 75mph

Funny I always thought vw were slower than Speedometer but most here report higher speeds.. Hmmm

Nebelwerfer · Oct 5, 2012

On Tom Tom, speed is 100kph....speedo is 105kph.

Joe_Meehan · Oct 5, 2012

Most all cars at of the factory will show a higher speed than the car is actually going. That is done intentionally to avoid explaining why you got speeding tickets, if there is an calibration problem.

GPS devices will usually be very accurate. The newer ones are the most accurate.

VeeDubTDI · Oct 5, 2012

Passats seem to err on the low side, which is a big change from every VW in the past that displayed high.

ColoradoDriver · Oct 5, 2012

VW seems to have fixed the problem when they came out with the 2013's. I adjusted my 2012 to be accurate, but when I checked a friend's 2013 before making an adjustment I found that it was already pretty accurate from the factory.

torontostreetsweeper · Oct 5, 2012

How do you adjust the speedometer on the Passat? I read it was not adjustable with vag com?

Any help would be greatly appreciated.

ColoradoDriver · Oct 6, 2012

torontostreetsweeper said:
How do you adjust the speedometer on the Passat? I read it was not adjustable with vag com?

Any help would be greatly appreciated.

Yes you can correct both the odometer and digital speed display to be much more accurate:
[Select]
[17-Instruments]
[Coding - 07]
[Long Coding Helper]
Click on each of the Byte numbers in row 3) and you'll see the selectable options below.
In this case, Byte 0 contains the "Distance Impulse Number".
2012 Passats are set at "3" by default. If you change that number to "2" it will improve accuracy when using stock wheels/tires.
In my case, using 225/50R18 tires, I changed the value to "1" and got the results I wanted.
That fixed both the odometer and digital speed display. The analog speedo is still a bit optimistic, but I usually use the digital speedo anyway.

Note: The 2013's seem to be accurate from the factory--so no adjustment necessary.

dubStrom · Oct 6, 2012

Shocked!

VeeDubTDI said:
Passats seem to err on the low side, which is a big change from every VW in the past that displayed high.

There's a permanent radar with "your speed" on a road I go on when I tank up (same place, every time!).

The Jetta Sportwagen was SPOT ON. This was my first pass in the Passat (first fuel-up!!), and it showed a typical positive error of ~1.5 to 2 mph. I was actually going a little slower than indicated on my speedometer. Good to know.

But I was shocked, shocked to see the range showing 710 as I drove out of the BP. Even more amazed as it climbed from 710 to 790 as I drove around the beltway about 7 miles home.

The shock was realizing that it is real! I drive that way on the highway, and I can expect over 800 miles on a tank. Damn! Am I happy (rhetorical question)?

VeeDubTDI · Oct 6, 2012

dubStrom said:
There's a permanent radar with "your speed" on a road I go on when I tank up (same place, every time!).

The Jetta Sportwagen was SPOT ON. This was my first pass in the Passat (first fuel-up!!), and it showed a typical positive error of ~1.5 to 2 mph. I was actually going a little slower than indicated on my speedometer. Good to know.

But I was shocked, shocked to see the range showing 710 as I drove out of the BP. Even more amazed as it climbed from 710 to 790 as I drove around the beltway about 7 miles home.

The shock was realizing that it is real! I drive that way on the highway, and I can expect over 800 miles on a tank. Damn! Am I happy (rhetorical question)?

Does that make up for the lack of a convenient key hole?

dubStrom · Oct 6, 2012

VeeDubTDI said:
Does that make up for the lack of a convenient key hole?

I was totally unaware of the "all windows down" feature on the driver's door window controller. I still think it is stupid to hide the keyhole, but I can live with it!

passsattdi · Oct 7, 2012

dubStrom said:
There's a permanent radar with "your speed" on a road I go on when I tank up (same place, every time!).

The Jetta Sportwagen was SPOT ON. This was my first pass in the Passat (first fuel-up!!), and it showed a typical positive error of ~1.5 to 2 mph. I was actually going a little slower than indicated on my speedometer. Good to know.

But I was shocked, shocked to see the range showing 710 as I drove out of the BP. Even more amazed as it climbed from 710 to 790 as I drove around the beltway about 7 miles home.

The shock was realizing that it is real! I drive that way on the highway, and I can expect over 800 miles on a tank. Damn! Am I happy (rhetorical question)?

Just wait. I have hit 900 miles per tank . It just keeps getting better.

Went in for my first 10k changge which is the first time the dealership saw the car since it rolled out. My MPG readout changed for the worse. But the actual mileage hand calculated was better. I think they are fixing the 12s now too.

ColoradoDriver · Oct 7, 2012

passsattdi said:
......... I think they are fixing the 12s now too.

Thanks for the heads-up. I will need to be sure that they do not screw mine up, since I am running taller tires and am set up correctly now.

NSTDI · Jun 20, 2013

ColoradoDriver said:
Yes you can correct both the odometer and digital speed display to be much more accurate:
[Select]
[17-Instruments]
[Coding - 07]
[Long Coding Helper]
Click on each of the Byte numbers in row 3) and you'll see the selectable options below.
In this case, Byte 0 contains the "Distance Impulse Number".
2012 Passats are set at "3" by default. If you change that number to "2" it will improve accuracy when using stock wheels/tires.
In my case, using 225/50R18 tires, I changed the value to "1" and got the results I wanted.
That fixed both the odometer and digital speed display. The analog speedo is still a bit optimistic, but I usually use the digital speedo anyway.

Note: The 2013's seem to be accurate from the factory--so no adjustment necessary.

A friend changed my 3 to a 7, now very accurate, within 1 KPH, speedo is slower than GPS.

My cruise kicked itself off 3 times after doing this change- in an 85KM trip. Any possible connection between the speedo fix and the cruise issue?

Don

AreaMan · Jun 21, 2013

Another data point from my 2013:
65 mph on the MFI display = 66 mph on the analog speedo = 65 on GPS
So the MFI speed readout is dead on, and the analog speedo reads 1mph high at 65.
Haven't checked the odo accuracy, but I would think the speedo and odo use the same input, so they should be the same.

ColoradoDriver · Jun 21, 2013

NSTDI said:
A friend changed my 3 to a 7, now very accurate, within 1 KPH, speedo is slower than GPS.

My cruise kicked itself off 3 times after doing this change- in an 85KM trip. Any possible connection between the speedo fix and the cruise issue?

Don

I doubt that there is any connection. Only time I have seen the cruise disengage on its own is when I was going too fast into a curve. If ESP cuts in, the first thing it does is disengage the cruise control.

ColoradoDriver · Jun 21, 2013

VW apparently fixed the accuracy issues they had with the 2012 Passats. A friend's 2013 was dead-on when I tested it for him.

Sharky · Jun 21, 2013

ColoradoDriver said:
Yes you can correct both the odometer and digital speed display to be much more accurate:
[Select]
[17-Instruments]
[Coding - 07]
[Long Coding Helper]
Click on each of the Byte numbers in row 3) and you'll see the selectable options below.
In this case, Byte 0 contains the "Distance Impulse Number".
2012 Passats are set at "3" by default. If you change that number to "2" it will improve accuracy when using stock wheels/tires.
In my case, using 225/50R18 tires, I changed the value to "1" and got the results I wanted.
That fixed both the odometer and digital speed display. The analog speedo is still a bit optimistic, but I usually use the digital speedo anyway.

Note: The 2013's seem to be accurate from the factory--so no adjustment necessary.

Thanks for that information. I am still unclear on if the speedometer and odometer are related. For example, if the speedometer is off by 7% does that mean the odometer is also off by that same 7%. And further, does the solution as decribed above then also fix the odometer issue?

NSTDI · Jun 21, 2013

ColoradoDriver said:
VW apparently fixed the accuracy issues they had with the 2012 Passats. A friend's 2013 was dead-on when I tested it for him.

Mine is a 2013.

Don

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