Fuel Gauge and Miles left in Tank

DE_612183

Hi, I've got a fairly new car ( less than a year old ), I have a problem that the fuel gauge is got reducing with usage.
I reset the "trip" every time I fill up, and usually after a while the correct value is displayed - but I wonder what is happening.
I know in old cars there used to be a float, that would measure the tank contents - which was why if you parked on a hill the tank could show as full or empty depending on which way you were pointing!

Any ideas on what could be wrong and if there is an easy fix?

Thanks

daveyjp

A make and model of the vehicle could be useful info if you want a meaningful answer.  

As would details of which figure you are looking at on the gauge as your title mentions 'miles left in tank'.

On some vehicles the miles left resets each time you refill and does take time to recalibrate.  Others use the previous figure and adjusts from that figure.

Stubod

..if it's under 1yr old then I assume it's still under warranty?

DE_612183

it's an VW t-roc

DE_612183

Stubod said:

..if it's under 1yr old then I assume it's still under warranty?

Yes, but I bought it from a garage miles away - I can take it there but it's a pain - I wondered if this was a common problem that was easily fixed - for example if it is a float then I guess it may clear if the float the stuck and I dislodge it by going over a bump!

Or is it just very inaccurate!

jefaz07

Mine changes all the time. Mainly depending on how I’m driving. Sometimes if I fill up and go on a long efficient journey the ‘miles left’ goes up. 

Grumpy_chap

Warranty can be dealt with by an VW Dealer

DE_612183

jefaz07 said:

Mine changes all the time. Mainly depending on how I’m driving. Sometimes if I fill up and go on a long efficient journey the ‘miles left’ goes up. 

yeah, I get that - my problem is it hasn't changed - stuck on 485 despite ding about 30 miles

ontheroad1970

Warranty work can be done by any VW dealer, not necessarily the one you bought the car from

Grumpy_chap

DE_612183 said:

jefaz07 said:

Mine changes all the time. Mainly depending on how I’m driving. Sometimes if I fill up and go on a long efficient journey the ‘miles left’ goes up. 

yeah, I get that - my problem is it hasn't changed - stuck on 485 despite ding about 30 miles

That is a dynamic read-out though.
The accuracy of the fuel measurement is "rough and ready" to start with.  Then the estimated mileage changes, so if you drive 30 miles but do so more efficiently than the previous 30 miles, the forecast range can increase.
Does the forecast to empty decrease if you keep driving, or does it still say 485 miles when the car is on fumes?

At best, the forecast range and average mpg etc are all just indications.

DE_612183

Grumpy_chap said:

DE_612183 said:

jefaz07 said:

Mine changes all the time. Mainly depending on how I’m driving. Sometimes if I fill up and go on a long efficient journey the ‘miles left’ goes up. 

yeah, I get that - my problem is it hasn't changed - stuck on 485 despite ding about 30 miles

That is a dynamic read-out though.
The accuracy of the fuel measurement is "rough and ready" to start with.  Then the estimated mileage changes, so if you drive 30 miles but do so more efficiently than the previous 30 miles, the forecast range can increase.
Does the forecast to empty decrease if you keep driving, or does it still say 485 miles when the car is on fumes?

At best, the forecast range and average mpg etc are all just indications.

At the moment 485 has stayed that way for about 100 miles, then drops and works ok.

But I have to remember to set the trip when I fill up in case it stops altogether!