A3 Fuel Gauge over-reading, instrument cluster fault?

[Sly]

Sly's next fault to sort out is his fuel gauge, it overreads by about 1/3 tank. The low warning light comes on at the right time and there are no fault codes. Vag-Com says the correct level and the sender resistance looks good. When I do the output test the fuel gauge doesn't come back to half way as expected but stops at about 3/4.

I know this is common fault with the instrument cluster but I don't want to spend hundreds sending it away to get it fixed. Saying that, it CAN be fixed so just need someone to tell me how. I'm not bad with electronics, used to fixed TVs and stuff, someone out there knows what resistor or diode is causing this or has a wiring diagram of the cluster I can ponder over? Let's have it please!

This could help numerous people, ta, Sly.

[Sly]

I'm a bit impatient so I took it out to see if there's anything obvious, there isn't! But, it comes in and out easily and the back comes off to get at the circuit boards easy enough too. The temp gauge and fuel gauge look identical and have the same resistance readings across their coils. I'm guessing it must be a bias voltage or something that is too high for the fuel gauge. When I switch the ignition off the temp gauge goes left off scale but the fuel gauge stops on about 1/8 tank for a few seconds then eventually goes off scale. Part number for my cluster is 8L0920950C and has 008AUZ5Z0A1283167W whatever that means?!

[burkey1]

I know there is an off-set option on these guages as I carried this out this on an 02 beetle for different reasons.

You may be able to electronically off set your zero point with VAG-COM.

See link below for something similar..

http://www.vwaudiforum.co.uk/forum/showthread.php?t=104715

[Sly]

Cheers Burkey but alas, I have already tried the adaption of the fuel gauge, it lets me select between 120 - 136 which apparently should cover 1/8 tank, but this is not enough to correct my error. In fact, I didn't notice it move the needle at all so this may also be caused by the same fault? I'm interested now to hear from anyone who's tried this adaption, can you physically see the needle move much?

[burkey1]

Yes, I could physically see the needle move..

[Sly]

I tried to get some information out of Reman who fix this fault regularly but tehy refused to share it, understandably I suppose. When the ignition is switched off, the fuel needle hovers just over empty for a few seconds before going off scale like the temp gauge. It sits there when the key is at accessory as well, while temp is off scale. Any ideas?