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I have a 2003 Civic LX. My speedometer began reading about 15-20% higher than it should about two months ago. I verified the incorrect reading by comparing my speed to two other vehicles and a speed app on my phone. The other vehicles and the app all had the same reading while mine was higher. For example, my speedometer showed 70 mph while the others were at 60. My odometer is registering more mileage by a similar percentage (verified by known mileage).

The local Honda dealer checked my vehicle and said that the speedometer is reading correctly. The service write-up says "Checked speed with HDS and speed is correct". When I provided backup that it is not correct, all they offered to do was call Honda and see what they suggested - I am still waiting to hear back from them. Aside form the speedometer/odometer issue, the only other symptom I am having is that the cruise control started acting up around the same time - it maintains a speed, but I can feel it surging (as if repeatedly applying the gas and letting off). Does anyone have a suggestion or advise on getting the speedometer checked and fixed?

Thanks

 
Rep Power: 517

So they connected a scanner that showed the same speed that your speedometer is displaying.
Speedometer is doing exactly what the PCM is telling it to do. (possible GIGO?)


Seems that nobody (dealer techs) compared that scannerinfo against GPS? That's a problem.

Was any work done to the car two months ago?


What size tires are on the front of the car?

 
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The only work done around the time I first noticed the issue was a transmission drain and fill and I had to have the left front cv axle boot band replaced. The front tires are the same size as the original tires (185/70 R14).

 
Rep Power: 517

If the tire size is correct for the car,

I'd be tempted to try replacing the VSS and see what happens.

Or drive around with a phone app/navigation unit showing road speed and ignore the speedometer

 
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I have actually been using a speed app on my phone at times. The speedometer being off does not bother me as much as the odometer registering more mileage than it should.

I was shocked when the dealer told me that my speedometer was correct and that there was basically nothing else they could do. I may try replacing the VSS as you suggest.

 
Rep Power: 118

 
Rep Power: 517

I would not think it possible to be that......


Um, Does OP have a manual trans, or automatic?
Maybe you should get a scanner of your own so you can verify the speedometer really is displaying exactly what the engine computer is seeing, via live data list

 
Rep Power: 0

 
Rep Power: 517

Guess you could spend money on a speed sensor and see if that changes anyting.....or use the GPS for free instead
The car is old enough that mileage probably matters very little on resale value.
My state doesn't care about accurate mileage after 100,000 when transferring a title.