Scangauge MPH reading

[Brownfaux]

Simply put, the scangauge doesn't match the speedo. Speedo shows me going faster than I am.

I'm guessing a previous owner had bigger tires and adjusted the speedo for it? But then why would the scangauge be off if it's reading from the ECU? Could there just be some variance?

I searched "scangauge speed" and didn't see anything relevant. Sorry if I missed it.

 

[mikebontoft]

how far off is it though?

 

[Brownfaux]

About 1 to 3 mph. Gap increases with speed. I'll have to write it down next time I'm on the freeway.

 

[mikebontoft]

that's about normal. until very recently, most manufacturers set their speedometers to read about 2mph higher than your actual speed. I'm not sure of the reasoning behind this though.

In other words, yeah it's normal.

 

[wrestler157]

You can change it, it is kinda dangerous as you do it driving down the road or have someone do it beside you. Pm me ill give you directions how to do it

 

[Brownfaux]

That makes sense. I thought there may have been variation because the speedo is mechanical, but scan gauge is getting from the ecu so that must be right.