Speedometer error on Toyotas

[SHOZ]

My Gen Coupe was off speedo and odo wise. I put one inch taller tires on and got the speedo near dead on but the odo is still off by 5% slow.

 

[Nick1994]

My aunt's 2016 Avalon read 2 mph fast with the needle but the digital speedometer was spot on

 

[Nac Mac Feegle]

I have two '90's Civics, each has a Scangauge II permanently plugged into the ECU. The speedometer reads high on both cars, but checked against a GPS the computer is dead nuts, as is the odometer. It knows exactly how fast it's going, it just doesn't want to tell me. The Camry speedometer, on the other hand, reads high but it's an accurate reflection of the ECU output. I have not checked the Toyota odometer.

 

[97prizm]

I think in the 2000's Honda had some off by 8-10% and some owners sued for warranty loss, IIRC, and diminished resale value? 8% is a lot.

They also were sued when it showed that the miles and kilometers weren't racking up equally.

 

[JohnnyG]

They know the "correct" speed and that is used for the odometer. They use another doctored value for display as speedometer output. Edit- @Quattro Pete beat me to it.

It can't "know" the correct speed if the tires were changed. The only way to know the actual speed, once components are changed, is to either adjust for the changes, or use GPS.

 

[chris719]

It can't "know" the correct speed if the tires were changed. The only way to know the actual speed, once components are changed, is to either adjust for the changes, or use GPS.

No one said it would be accurate if you changed overall diameter of the drive wheels unless I am missing something.

 

[Highboy]

2008 Highlander reads 2-3 faster than actual speed.
2006 and 2008 Scion Tc about right on to 1 mph fast.

 

[Kestas]

A person can calibrate their speedometers on a freeway with light traffic.

Using the mile markers, run the car at a steady 70 mph for 10 miles while using a stopwatch. Do this at 60 mph and at higher speeds if you dare. Do the math from there.

 

[Gasbuggy]

Honda got sued over this. Helps them with warranty and leases....

 

[i6pwr]

SAE specifications require speedometers to be accurate -1% / +3%

Then if I'm showing 50 but actually traveling 47, that's roughly 6%.

Can’t speak for Toyota, but all my Mopar’s have been dead on according to GPS and those mobile speed checks. I’d be driven nuts if they weren’t.

Definitely drives me nuts, lol. If you don't think about it especially when driving through town or slower speed zone, you are the one annoying others by driving too slow...lol.

Is 3 MPH a huge deal, not really, but the point is for the driver to be aware of their speed and make adjustments accordingly. If you get a ticket for being 5 over that's on the driver.

I absolutely see no problem the 1 MPH error, factors in tire wear, viewing angle of speedo needle where applicable.

I also agree better to err on the low side when you roll past a popo.

 

[Marcozi]

My car's speedo is spot on at 60mph and 100mph. I used the GPS app speed box to check it.

 

[Hermann]

When I had the 2008 Tacoma it was finally spot on when the OEM tires were replaced with one size larger, same aspect ratio.

 

[eljefino]

Took the Camry my son drives, and replaced its 195-70-14s with 215-60-16 snows. Speedometer is perfect and it has more ground clearance, LOL.

 

[CR94]

They know the "correct" speed and that is used for the odometer. They use another doctored value for display as speedometer output. ...

Yes. On my Toyota, I can see three different opinions of my speed---1) the "doctored" value prominently displayed on the instrument panel, 2) the number shown by my GPS navigator, and 3) the speed the car's computer considers to be actual speed, which is readable via ScanGauge plugged into the OBD2 port. At ~60 mph, the instrument panel shows about 1.5 mph above GPS speed, on average, with the present tires. Speed from the OBD2 is roughly midway between the others. Odometer shows about 1% high.

On the same car with its previous tires, which were the same nominal size, the odometer was near perfect, and speedometer error was proportionately smaller too.