03 TDI Jetta Fuel Gauge not working.

Try a new fuel sender?

Try reading the level with VCDS, if that reads ok, then you know you have a gauge issue.
Try reading the resistance at the fuel sending unit under the rear seat. The resistance between the center two pins should be between ~50 to ~250 ohms, and it should vary with fuel contained. If the resistance is good, then you know it is not the fuel sending unit. If it is bad, then it is the fuel sending unit.

If you buy a Bentley manual, you can see the wiring diagrams and troubleshoot further, pinning it down to a faulty wire between two connections perhaps.

And stick a 250 ohms resistor in the fuel sender connector. If the cluster read full, then you have a bad fuel sender.

Tom,
After about 2 mins searchin for sender or sending in the title, this is what i came up with. It can be tough to find the right word to search for. this shows how to clean the sending unit, not hard to do, just do it when the tank is low.
http://forums.tdiclub.com/showthread.php?t=282173&highlight=fuel

Thanks for the info guys. I found my problem when I removed the fuel sender plate under the back seat. Can you say there was a very busy mouse? See my photos to see how much they chewed through the connector.
http://www.tommarkhamphoto.com/tdi/sender.htm

MMMMM yummy wires Time to visit the junk yard 4 a connector.

I was able to temporarily fix it with wire nuts and electrical tape. I will be looking for a connector for sure. The fuel gauge died about 3 months ago and I believe the culprits are long gone. I don't know how they got in there except along the channel from the fuel lines. Even more impressive is how they got acorns in there.

I'd set some mothballs in there just in case!

Whoa! They ate through the connector too?! Those little things will eat anything. At least its easy to get to from the inside. Must be nice knowing what the problem was/is.

bora fuel guage sticking

eh oh all. just to add to this topic. just run out of fuel today. after checking the sender and the gauge with a multimeter. had the sender connected and worked the float and gauge was moving fine and the light was comin on. now i put it in the tank it reads 1/4. and hence i ran out of fuel. any ideas would be lovely. cheers

Do you have the fuel sending unit aligned correctly? There is an arrow on it that must be pointed straight back.

I'm in the same boat. I filled up the other day, and the gauge only read 1/4 tank. I turned the key off and on a few times and it went up a little more each time till it read full. After that it's hit or miss. Fortunately I use the trip miles so I know about where I am.. But definitely want to fix it. Where'd you all go for the parts? ID parts?

Remove the sending unit and clean any point where wires connect to terminals. Films form over years and the film changes the resistance, which changes the gauge readings. This fixed mine and it's been good for over 2 years now.

I have an intermittent issue with mine. Occasionally while driving, I will notice on empty. I can turn the key off and back on, then the gauge reads correctly.

Very sporadic. Notice it every week or 2.

Hello. I'm new to this forum. I have an 03 jetta that has the same fuel gauge issue. If I replace the sending unit odor even take it out to check it, do I have to reptile my fuel system or just fill it back up before cranking? Thanks.

Hello. I'm new to this forum. I have an 03 jetta that has the same fuel gauge issue. If I replace the sending unit or even take it out to check it, do I have to reprime my fuel system or just fill it back up before cranking? Sorry for all the grammar mistakes in the first post Thanks

Welcome to the forum. If you only replace the sending unit you should be able to restart without any issues. Meaning, do not disconnect any other fuel lines other than the 2 connections at the sending unit. The filter will remain full and restart should be normal, just be sure to let it run for at least 5 minutes and take for a 10 minute drive that sure clear any air in the lines.