406 hdi fuel gauge accuracy?

[deano1970]

hi,
I have had a peugeot 406 hdi 2001 for a few months, I parked it down town yesterday and went for a drink. picked it up this morning and the fuel gauge is showing slightly over half.When I parked it up it was about a quarter, I parked it on a hill facing down and obviously put it down to that, but even now it has been parked on the flat, the gauge is still reading half full when I know it isn't?

why would this be? cheers,

dean..........

[Peter.N.]

I have had variable readings from mine, it once told me a had a full tank when I knew it was only just over half full but corrected itself after a couple of days. We came back from Scotland last week and managed over 1000 miles on a tankful and didn't run out! so I think it must be pretty accurate overall.

Peter

[BX]

It must have been a very steep hill. Fuel gauges nowadays are not what they used to be. To ensure accuracy they will only read when the vehicle is parked on level ground. It is assumed that filling stations are on level ground. So, if the gauge detects an increase in fuel level which corresponds to more than a minimum amount e.g. 10L whilst the vehicle is stopped it registers this on the gauge on the dash. It assumes that the tank has been topped up and that the car must have been filled on level ground. The minimum amount is chosen to avoid the situation where a slope causes the gauge to register an increase. As fuel is metered very accurately by the engine management system the ECU now knows how much fuel is drawn from the tank as you drive along and decrements the gauge accordingly. Most modern vehicles (including petrol cars & HGVs) have an in tank pump which depends on the fuel in the tank for lubrication & cooling. Also it does the modern high pressure fuel systems no good at all to become airlocked. As a result several strategies are adopted to ensure that the tank never empties completely. In a commercial vehicle which is very popular in the UK the F**** T*****t a miss and judder is simulated by the injection system if the driver insists on driving on after the gauge shows empty. This is to frighten same driver to fill up as soon as possible. Other makes will stop shortly after the gauge reaches zero but will restart if the driver really insists on it. They will then drive for another 20 to 30Km and stop again. If the driver really tries hard i.e. keeps operating the starter they will restart and travel 10 to 15Km before stopping again. This time they will not restart until they are refuelled. If a car runs out of fuel more than 10L is required in most cases to get it to restart.
If you refuel most cars with the engine running the fill will not register on the gauge.
Back to your problem. All should become good the next time you refuel the car

[Peter.N.]

Interesting - thanks