2009 Passat CC (2.0L TDI) - Fuel Gauge Stuck

[Intestinalworm]

Hello There From Australia!

I have a 2009 Passat CC 2.0L TDI (CBBB engine) 6 spd DSG. The vehicle has done 103,000 miles.

Several weeks ago I ran out of diesel - strangely the MFD said I had 60 miles before the tank would be empty - apparently, not so! Before this the MFD struck me as being very accurate as far as estimating distance to empty.

All good after that initial tank refill until yesterday; because my wife and I sometimes drive the car she thought I had been re-fuelling and I thought she must have been refuelling; no one had been refuelling - looks like the gauge is permanently on 40% full!

Can anyone please tell me if this a common problem (stuck fuel gauge)?

I was going to fill-up with diesel from a jerry can, but before I do, I thought it might be better to remove the in-tank electric pump and check the float and sender unit?

Any thoughts?

Is there a run-through somewhere that might help me diagnose/fix this issue?

Kind Regards, Paul.

 

[nayr]

very cool a TDI CC..

Does it do a needle sweep on start? or can you VCDS it to do a needle sweep? That might see if its got full range of motion.

otherwise, I'd start off at the float on the lift pump.. you should be able to take it out, plug it back in and play with the float and see the needle change.. last time I had a stuck fuel gauge that was the issue, but it was a 1975 VW, not a 2009 heh.

 

[Intestinalworm]

very cool a TDI CC..

Does it do a needle sweep on start? or can you VCDS it to do a needle sweep? That might see if its got full range of motion.

otherwise, I'd start off at the float on the lift pump.. you should be able to take it out, plug it back in and play with the float and see the needle change.. last time I had a stuck fuel gauge that was the issue, but it was a 1975 VW, not a 2009 heh.

Yes, quite a few TDI CCs in Australia (relatively speaking!). Thanks for the feedback! I see you're from Colorado? A few Aussies (with lots and lots of money!) were skiing in your neck of the woods and they came back to Melbourne here in Australia with a special "gift" - "COVID-19"; apparently they refused to be tested in the US so they could keep skiing and partying!!!

Anyway, we are socially isolating now, so I'll get some time to check the gauge (do a sweep) with my Foxwell scanner as you mention - that will tell me if the gauge is okay hopefully. If it is, I'll disconnect the battery negative terminal then pull-out the pump/sender-unit/float. I assume I can put the pump in a bowl/bucket and reconnect the electrical plug and then battery negative terminal, move the float and see if the problem is with the sender unit by checking for movement at the gauge?

 

[nayr]

Ive got a 6MT CC, those are about as rare of a CC as we got..

More than likely you just need to lift the pump up a little bit to reach in and manipulate the float with a screwdriver or something.. but it might needa come all the way out, you'll want to keep the diesel spills down to a minimum so whatever you come up with.. If your tank is full now, I'd track millage and wait til you knew it was closer to empty than full just so you reduce your spillage.

 

[Intestinalworm]

Ive got a 6MT CC, those are about as rare of a CC as we got..

More than likely you just need to lift the pump up a little bit to reach in and manipulate the float with a screwdriver or something.. but it might needa come all the way out, you'll want to keep the diesel spills down to a minimum so whatever you come up with.. If your tank is full now, I'd track millage and wait til you knew it was closer to empty than full just so you reduce your spillage.

Tank is empty - will keep plenty of old towels in case of diesel dribbles - don't want any diesel on seats/carpet - smell will never go away!! If not gauge, then maybe stuck float?

Just realised, I don't think I can connect the pump to the electrical plug when it's out of the tank and then manipulate the float to see if the gauge changes because ignition in on position would cause pump to start running (dry)!

 

[nayr]

you can take it out and test em with a multimeter, fuel senders are all pretty standard..

skimmed this article and it seemed pretty good: https://www.sailmagazine.com/diy/test-replace-fuel-gauge-sending-unit

 

[Intestinalworm]

Okay, can't find multimeter - hunted high and low - will buy a cheap one tomorrow. Thanks for the article link.

Used Foxwell diagnostic tool to check fuel gauge - sweeps - no issue; low fuel warning lamp good as well. No engine fault codes either. Put fob key in to ignition and fuel gauge needle goes up to 40% again - where it has been for a while now as I mentioned earlier! The tank is empty (no diesel) - engine won't turn over. [This has happened before and had to put diesel in with a jerry can, prime with the Foxwell and then start.]

So, pulled bottom of rear seat off and disconnected seat heater loom. There is a rubber tight fit cover (no screws) - managed to prise off getting fingers underneath. Okay, getting dark now so will finish tomorrow - will vacuum all the dirt off first! There is the snap on fuel return and fuel to engine lines but couldn't get the electrical plug off - moved the little red piece up and tugged on it - nothing, almost as if it's glued on! Don't want to break it, so might spray some penetrant on it tomorrow and try again.

Funny thing, had a look at YouTube and seen this: https://www.youtube.com/watch?v=6ccVHowG_8s

Can't work this one out (YouTube video) - he seems to fix his fuel gauge error by just removing the in-tank pump and just putting it back in again with some additive???

 

[Intestinalworm]

Apparently VW dealer does sell sender unit for the pump (available ex-Germany on couple of weeks delivery) for AUD294.

Pump (including sender unit) from dealer is AUD683.

Will pull pump out (just struggling to disconnect the stubborn electrical connector - will try pushing the red tab down and pulling up, rather than red tab up) and check sender unit variable resistor for damage/dirt and then check smoothness of resonse with multimeter resistance test.

 

[nayr]

german electrical plugs are like those brain teaser puzzles they used to give us as kids, good luck.. If all else fails find an old VW hippie, they can pop em off w/one finger.