Can I change the Speedometer Correct Factor?

Discussion in 'Gen 4 Prius Technical Discussion' started by ticedoff8, Jul 26, 2025.

  1. ticedoff8

    ticedoff8 Junior Member

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    I have a 2016 Prius Touring model with the digital speedometer.
    Is there a setting in any of the car's ECUs that I can change (and write) for "Speedometer Correct Factor"?

    Since I changed the tires, the speedo readout is about 4% lower than my phone's GPS says (Example: 55MPH speedo v. 53.5 on GPS. 77MPH on the speedo v. 74.5 on GPS).
    It's always been a little off even with the tires that came new with the car (I bought the car new from the dealer), but now it's bugging me.

    I have an OBDLink OBD2 adapter and their OBDLink app with its 2016 Prius enhanced package.
    From what I can tell, the app is getting speed from the tablet's GPS and not the ECU - it matches my phone's GPS reading and not the speedo readout.

    Or, is there a screen that I can look at on the car's LCD display that will do this?
     
  2. ticedoff8

    ticedoff8 Junior Member

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    Well, I can see this was beat to death on this other thread. But on a Gen3. I presume it's the same for a Gen4.
    If you sort through the "... it's a government conspiracy" posts, it comes down to "It can't be changed".

    I guess I'll just use my OBD2Link Bluetooth OBD2 adapter to my 7" Android tablet with the OBDLink app and mount it on the dashboard as a HUD to see what its GPS reads while I'm driving.
     
  3. Joe Dipierro

    Joe Dipierro Junior Member

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    My 2016 always reads about 2mpg slower when I use gps apps it drives me crazy
     
  4. Georgina Rudkus

    Georgina Rudkus Senior Member

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    You can get a cheap GPS speedometer off of Amazon for about $15. Mine has a 3/4 inch bright display and plugs into a USB port.
     
  5. Paul Gregory

    Paul Gregory Senior Member

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    Or a free phone app.
    No thanks.