There are two fuel level sending units on the G35. My gas gauge always reads empty but the low fuel level light always comes on. Does anyone know if the passenger or driver's side sending unit control the low fuel light?

If it helps, the service manual says the passenger side is the primary unit and the driver's side is the secondary.

 

I think they're meant to work together as opposed to one versus the other. This clip below from the schematic shows both senders simply in series.

My crude understanding is that the fuel gauge itself is designed to move slowly - so it's not swinging up and down the whole time you're driving - and the reason for two senders is if your car is tilted one way or the other the two senders even out the difference (one has more resistance while the other has less). I think the warning light only comes on when the total resistance reaches some specific number indicating both floats are at the bottom of the tank.

You may be able to diagnose which side has failed by stopping your car on a tilt, checking the gauge, then turning the car around to tilt the other way and seeing which way the gauge moves. If it goes UP when the car is tilted to the right then the passenger side sender may be OK. How's that for a low-end diagnostic?

 

clean the passenger side first. it has the lever float on that side. it's the side I would try first.

And clean this part. it has lines on it, use a q tip.