obc fuel capacity reading

[gazza]

i have a 13 button obc on my cab,when i fill my car to the brim it can take up to 58 litres to fill it. but if i press the 1 and 1000 settings it shows 46.5 litres i have tried to adjust the screw in the bottom left of the obc but it never moves . i will then run it as low as i can the range button is just about right, goes to as low as 9 miles and then shows m----- but when i press 1 and 1000 it shows a capacity of 11.5 litres this is when the red light on the fuel gauge and has been for 30 odd miles. my main question ....other than the small screw on the obc is there any way i can adjust this to read correctly (the car has the correct code plug) the other problem is the obc shows an average mpg per tankfill of 19.6mpg when i have worked it out to about 27mpg my car is a m40 1.8i and most of the mileage is motorway driving

[gazza]

posted in wrong thread pls help

[HartgeH27]

helped !!!!!!!!!!!

[Widge]

Mine does this too, but it's a 325 with factory fit OBC, what's the solution?

[dazleeds]

mine too

can fill tank and still reads 20litres less than there is
poxy obc waste of time imo

never once had an accurate reading from it yet