Trip computer not accurate

[stu_no_1]

My average mpg on my trip computer is miles out when it says 20mpg its really about 25mpg when i work it out on how many miles i got from so many litres has anybody else got this problem and can it be fixed the funny thing is the miles till empty is quite accurate so i just go by that

[big al]

Have you pressed the reset/ok buton on the bottom of the stalk by accident? On the screen there should be a number 1, if there is a number 2 then it is showing average MPG, etc.
Just press the button once and it should change it back for you.

[Richn83]

The computers are generally a bit in accurate, the speedo itself is generally in the region of 10% out, the computer will also be rounding off figures, and have a sampling rate which will all add in-accuracies there is an ability to add a correction factor in VCDS for the speedo not sure if this would also alter the consumption value. 

[stu_no_1]

Have you pressed the reset/ok buton on the bottom of the stalk by accident? On the screen there should be a number 1, if there is a number 2 then it is showing average MPG, etc.
Just press the button once and it should change it back for you.

no ive not pressed anything by accident i know how it works it just it always read about 4 or 5 mpg lower than im getting the highest ive ever had was 30mpg but i done nearly 400 miles on the tank this worked out at nearly 40mpg so im thinking its maybe a percentage out as the gap has got bigger as the number it displayed got higher

[stu_no_1]

anybody help me out with this?

[vRS Carl]

You can accurise the Trip Computer.

Work out the actual MPG figure from a full tank

Number of litres added / 4.54 = number of gallons used

Actual MPG = distance on full tank / gallons used


Go into VCDS/VAGCOM, open controller 17, Instruments

Click advanced functions, Adaptation box 10

Scroll up to channel 3

Standard default value = 100%. This can be altered withing the range 85% to 115%


Work out new value this way:

New % figure = (old % figure x MPG figure shown on dash) / calculated actual MPG figure

I have done both my cars and it's pretty much spot on now 

Disclaimer: Neither I nor MK5GolfGTi will be held responsible if anything goes wrong. If you do this procedure you do so at your own risk!

[vRStu]

I've added this to the VCDS Tips & Tricks Carl     

http://www.mk5golfgti.co.uk/forum/index.php/topic,121.new.html#new

[vRS Carl]

Cheers Stu