2002 Ford Mondeo fuel gague not working + low fuel light on

Sounds like a faulty tank unit (sender unit ) but could check wiring at unit also .

Thanks for the reply to original question, i have disconnected the wiring terminal from the tank unit expecting the light to go off but it stays on. Is there a regulating module or something somewhere?,Any ideas?. Thanks, Doug.

If the sender unit becomes stuck in one position (could even be the full position) after a while many cars will detect the fact that the fuel level has not dropped despite the fact you have driven several hundred miles. The guage will then display empty and a warning light comes on. If you disconnect the battery for a minute then reconnect it the fault may temporarily disappear and will prove a sender fault. This fault often shows up on LPG converted cars as the car doesn't use any petrol.

Have you had a look at this similar problem:

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Thanks for the help.
Problem was "open circuit" in the tank sender unit, all fine now. Doug.

Have you had a look at this similar problem:

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yep i have a problem that my fuel gadge sometimes says empty & light on when its either full or even 15 ltrs or 3/4 fuel then suddenly its will read either full or 1/2 full etc light goes out i never know now exactly how much is in tank last week i fiiled my tank to capacity 58,5 ltrs full my receipt at pump said 44.5 ltrs went in to fill tank up meaning 14 ltrs was left in tank before i fiiled up but one min it reads full then empty or 3/4 just pain anyone have an idea or know how to get it sorted pls