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While in Engineering Mode on the digital speedometer, it shows 1 MPH lower than what is set on the cruise control. When I check with my GPS app, the speed is accurate with the cruise but not the digital display. Is there anyway of adjusting this?
Your speedometer was not intended to be perfectly accurate; most of them are set to read a small percentage fast at average speeds. All measuring devices have some inherent error, and the manufacturers bias that error on the side of safety and compliance. Your speedometer was set to keep the driver slightly under the speed limit instead of potentially slightly over. It reads closest to actual speed when you have new tires; as tires wear down, their circumference decreases and the distance the vehicle changes per rotation, which is what your truck's speedometer is actually counting and displaying, changes a little bit. By comparison to GPS, I've found that the speedo on my last 3 vehicles typically read about 1 mph fast at highway speeds with new tires. At street speeds it's some fraction of 1 mph. My F150 analog and digital speedometers match.
You can correct by using Forscan to adjust your tire circumference, but it will never be exact, and the small error is not a flaw needing correction.
It's been a long time since I looked it up, but when I did the FMVSS regulations allowed the speedometer to be up to 10% off actual. Kinda crazy they allow that much. For the record, my digital speed display is correct and the analog gauge is off by 1 mph.
I'd like to clarify that the issue isn't a digital/analog discrepancy, and the tire size would affect the difference between digital and the GPS, but not the difference in the digital and engineering mode speedometer. Attached are pics of what I'm referring to. As you can see, the digital and cruise agree with each other, but the engineering mode is actually showing the correct speed compared to GPS. I'd just like for at least the digital/cruise and engineering to agree with each other. I don't pay attention to the analog because it's off anyways due to it being a gauge conversion from when it came into the US from Canada.
Last edited by firemanjj82; Dec 25, 2025 at 01:52 PM.
I'd like to clarify that the issue isn't a digital/analog discrepancy, and the tire size would affect the difference between digital and the GPS, but not the difference in the digital and engineering mode speedometer. Attached are pics of what I'm referring to. As you can see, the digital and cruise agree with each other, but the engineering mode is actually showing the correct speed compared to GPS. I'd just like for at least the digital/cruise and engineering to agree with each other. I don't pay attention to the analog because it's off anyways due to it being a gauge conversion from when it came into the US from Canada.
It's rounding up, for the reason I've already explained. I don't know how you would make them match since the IP digital speedo doesn't display in tenths of a mile per hour.
This has been my experience with my current 2018 and my 2023 company F150s. However, on my 2023, the cruise control matches the analog speedo (I rarely use the digital one) up to about 60 mph. But for me to achieve a 62 mph cruise, I have to set the cruise control at 61 mph. That pattern is consistent for any speed north of 60 mph (up to legal limits, as I can't/won't verify what happens past that) in my 2023. A tech at the dship told me the analog speedo is the one to trust, FWIW. A fraction one way or the other doesn't mean much to me.
Digital Speedometer Off
