I thought I'd post this here although it's not really FORScan-related for anyone interested in trying. The following describes the LOM (Lie-O-Meter) aka the fuel mileage reported on the cluster.
The following was posted by member Kingofwylietx here on the F150forum:
https://www.f150forum.com/f118/fix-inaccurate-lom-2-minutes-421912/#post5852007
The LOM is known to be pretty inaccurate for most of us. The good news is that you can fix it quickly and easily in 2 minutes with no tools if you know roughly how far off it normally is...
This was posted on another forum, but I thought it was too helpful not to share. Note, I used it for the 8" display size and it worked perfectly. I modified the procedure to be more clear than what was posted on the other forum. I have not tried the 4.2" display procedure because I don't have that one. I did this and my next fillup was accurate to within 0.1mpg.
FIST!!
Take your hand calculated MPG and divide it by the LOM display MPG....then multiply by 1000. This new number is what you will change the AFE Bias to.*
Mine worked out to be 934 because my hand calculation was 18.3mpg and my LOM said 19.6mpg. Example: 18.3/19.6 = .9337xxxx. Multiply by 1000 gave me 934 (I rounded up) as the number to use.
For Lariat and up 8 inch Display:
Engine off.
1. Press and hold OK Button on the left side of the steering wheel and don't release it until the end.
2. Press push start Button only (Not Brake Pedal) to turn to*Accessory Mode.
3. Once Message “Accessory Mode” appears.... press the Brake Pedal and turn the Engine on.*
4.*Engineering Test Mode*appears instantly. Release OK button.
5. Scroll to AFE Bias and push OK to change it to the number you calculated. Note, it takes quite a few clicks to get to AFE Bias.
6. Once done, turn off truck and it will update your mpg, including your Trip 1 and Trip 2. You'll see it has changed the next time you start the truck.
For 4.2 inch Display:
Engine off.
Press and hold OK Button on the left side of the steering Wheel.
Turn the ignition on Accessory mode only.
Continue holding OK button for about 5 sec until*"Engineering Test Mode"*appears.
Turn the Engine on and go through the menu pressing and releasing OK Button until you reach*"AFE Bias 1000"
appears press and release*Down.*Using*Left*and*Right*change 1000 to the Number You calculated. Press OK. Actually the steps how to correct the Numbers appears on the screen once You reach*AFE Bias. To leave Engineering Mode after you are done, just turn the engine off.