Passat B5.5 trip computer correction

[PeteK]

Does anyone know how to correct the trip computer reading on an 2004 Passat 130 Highline? The average mpg reading is always approx 10% optimistic on mine, I always fill up and work out the consumption manually and then compare the two readings. I'm sure I once read there is a way of correcting this by changing a value in the instrument cluster with Vag-Com.

[PeteK]

I found another post on an Audi forum regarding this, it states that if you enter controller 017 (instruments) you can change the value on adaptation channel 03 from 85% to 115% to change the calculation of the average mpg value. However I have tried this on the Passat and it does not allow you to do so.

Does anyone have any ideas if there is another channel where the value is stored?