Hi,

I've recently purchased a 2005 545i. I have found that the fuel gauge only read to just over half full. It appears to read correctly when I have less than half a tank but if I fill it right up, the gauge goes only to the half mark and stays there until I've used half the tank.
I started to check it today. Car has about 1/4 full tank. I took the cover off the right hand sender unit and with the ignition on, I disconnected the wiring plug, expecting to see the gauge drop to empty. It didn't - it stayed on 1/4. I then grounded the blue & white wire in the plug (which wiring diagram says is fuel sender). No change on the gauge.
Any ideas? Is there some sort of memory in the fuel gauge that takes time to reset? Am I doing something wrong?