Confirmed - Speedometer is incorrect - Is there a fix?

I think I saw a TSB out there for the Speedometer programming. Can somone confirm this? My speedo is off by 5 mph. Chad

I have gone back and forth with my dealer about this and no resolution offered. I am sure that my speedo is reading too high compared to reality and that means that my odometer must be running higher as well.

True...that means my car actually has 5000-6000 less miles on it. lol Chad

Can you say warranty claims for people who have exceeded their mileage allowance?

chad, i have the same thing. Everytime I pass those, for lack of better words, "speed reading machines", my speedo always shows 5+ mph higher. It is even more significant the faster I am going. There was a thread on this a couple months ago... this totally throws me off when im trying to "be good" on the highway because I can't tell how fast I'm really going (or conversly, how slow)

Are you sure this means your odometer is running higher? BMW's are notorious for this as well, but the speedos and odometers don't read from the same source. The speedo is read from a wheelspeed sensor, while the odometer reads from the differential. Comments I've heard in the past indicate there are severe panalties in Germany for a speedo that is reading slower than actual speed, so they (BMW, at least) intentionally have them read slightly faster than reality.

I wonder if the guys running 17" wheels have the same issue.

Only if their tire choice runs a different outside diameter than what the factory specifies. It's not wheel diameter, but tire diameter.

I'm not sure of anything other than I know that my speedo is not accurate.

Inaccurate speedometers are not on all cars. The digital guage on my 2004 C2 reads 1 mph high at 80. The analog one is exactly right. Tim

My digital speedo reads 121 when a GPS reads 119 FWIW

I don't believe Chad is comparing the digital vs. analog (may be wrong though). Cause my digital vs. analog is almost precise, but when tested against a speed detector, the reading is off!

I can't read the analog, the numbers are too close together. I never compared, but sounds like an interesting thing to do. I always assumed they were the same.

Let me tell you, that can be financially serious if it's off enough....if it's documented, and you go to trade your vehicle, it has to be carried by the dealer as a "mileage unknown vehicle", which diminishes its value dramatically....I bought an '00 S500 when they first came out, in mid '99, and on a long trip, I discovered that the odometer, and trip indicator were not collecting miles in tandem....I showed it to the dealer when I got home, and he told me about the mileage unknown situation.....he said he'd talk to MB about it....about 5 months later, he invited me to lunch, and threw me a set of keys....I asked what was up, and he told me that my new car was outside....they completely replaced my car...... There's probably a tolorance for how inaccurate the odometer is allowed to be...but I'd definitely check it out!!!!!!

True story? I'm going to be watching my odometer like a hawk now! 997 here I come!!!

Okay info. Spoke to the local stealer, err...dealer. He said Porsche notes to the techs a 10% (WTF?) allowable discrepancy. Hmm... He did confrim that the odometer is seperate and run off the dif. I am going to try and have the instrument cluster flashed to reprogram it. Maybe that will help. Who knows... C.

10%?????! WTF

I really think this is more common in German cars than many people realize.

Absolutely true....the dealer was Bruce Burnett, who owns Mercedes-Benz of Nashville......and he wasn't even the selling dealer!!!!! Mind you, that was a blatant problem, w/two digital counters running out of sync!!!

I got the same 10% message from my dealer when I asked. Mine reads about 5 MPH high but its more of an offset over 35 or so than a % delta. For example 40 indicated = 35 and 65 indicated = 60. The 10% threshold is at 60 MPG so I am within tolerance. Keep us informed if the flash fixes the issue for you Chad.

I used to complain, as many of us do, about the quality of domestic vehicles....but good 'ole American analog speedometers were the best!!!

So when you hit your 50K and the warranty expires, then you could potentially still have almost 5K left to get tot a true 50K. Sounds like a warranty scam to me I wonder how much it saves them in warranty work. Do the math.

That's what I wrote earlier but there isn't any data on odometers being incorrect that I have found.

I notcied the same thing a couple of months ago. Is it possible that ALL 996s have this issue?

I understand from previous threads on renntech.org that most 996s are about 5%-10% over on speedometers, but spot-on accurate on odometers. I must say, I don't mind that much--it means when I think I'm doing 80 it's only 72, so PAG is helping me keep out of more serious trouble with the law...

Ever drive by odo check points? We have them here in Oregon and my 2 miles on the odo rolls by faster than the markers along side the road. I'll have to check with my portable GPS unit.

My speedo also reads approx 5 kph (3 mph) fast at 60 mph. I had it paced against a couple of other cars (obviously not a precise measurement) and my speedo consistently reads a bit fast. I did ask the dealer about it when in for service. They said they checked it and it was "within tolerance". As I recall, hey said that within 5 mph is within allowed tolerance.