Fuel Gauge warning light

[string]

This is probably a really dumb question ,but when is the red warning light on the fuel gauge meant to light up?
At present the needle on my 89 320 can go well into the red zone without the light coming on.will it only come on past that or should it light up earlier. Even if I let the gauge go right into the red before filling I can still only get 50 litres at most in.

[Simon]

It does have to drop quite low before it lights up, but it does sound like yours isn't working though! Wouldn't advise letting it get so low though!

[Brianmoooore]

The red light on the gauge is the lower part of the whole red section. i.e. the light should come on when the needle reaches the lower side of the red painted area. Hope that makes sense - I'm not sure it would to me if I hadn't written it.

[nadz325i]

when i first bought my e30, i had the same question, someone suggested to drive around on low tank, with a petrol container (with petrol init ) and check when the light turns on.

mine more less comes on below the red square,about on the white line (with R onit), when it get here the obc shows 3.5 litres and miles range is about 30 miles.

[string]

Thanks guys. I will have to keep a can in the boot just in case and see what happens. I havn't let it drop right past the red square yet and the OBD shows 20 miles when i am in the red. I have a feeling it might be faulty but theres only one way to find out!

[Brianmoooore]

Next time you're as low on fuel as you dare, park with the RH wheels on as high a kerb as you can find. Wait a couple of minutes and see if the light comes on then.
I would imagine BMW design the OBC to be a bit on the conservative side.