# fuel gauge not working



## iluvmcr (Jan 14, 2005)

*Problem:* Fuel tank near empty and the gauge (appropriately) reads near empty. I pull in to a gas station and fill up. In spite of a full tank, the fuel gauge is still near empty and the warning light/chime is still on. I turned the car off and restarted it several times but no change.
Has anyone had this problem? Are there any past discussions on this? I can't recall any and could not find any reference in the table of contents.


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## pretendcto (Nov 23, 2005)

*Re: fuel gauge not working (iluvmcr)*

Did you check if it worked after locking the car for at least 2 minutes and staying away from it if you have keyless entry? I'm curious because I've had to 'reboot' my car this way after trying to get the car to get out of 'jack mode'. Of course, it could be defective fuel tank sending unit, fairly common on Audi's due to the sulfur content of US fuel. Something like that.


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (iluvmcr)*

What he said... (Paul)
Michael


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## iluvmcr (Jan 14, 2005)

*Re: fuel gauge not working (PanEuropean)*

thanks
I'll try a reboot after it sets a while.


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## copernicus0001 (Nov 30, 2004)

*Re: fuel gauge not working (iluvmcr)*


_Quote »_*Problem:* Fuel tank near empty and the gauge (appropriately) reads near empty. I pull in to a gas station and fill up. In spite of a full tank, the fuel gauge is still near empty and the warning light/chime is still on. I turned the car off and restarted it several times but no change.
Has anyone had this problem? Are there any past discussions on this? I can't recall any and could not find any reference in the table of contents.


I had the identical problem... It would only happen occasionally (maybe 5 or 6 times over the period of a year) - and over a few days of driving the needle would slowly creep up to where it belonged and start functioning properly.
I thought it was a sticky float - and wasn't too bothered by it - at least not enough to have the car pulled apart. As I was taking the vehicle in for its 20k service last week, I stopped to fill the tank... and it happened again. So I had the dealer look at it while it was in for its routine service. After a number of tests, they came to the conclusion (with the aid of a technician in Auburn Hills) that there was a problem with a gear or some other internal component within the gauge in the dash. They replaced the instrument cluster (it is a single large component). The vehicle has not been driven enough since the repair to need to fill the gas tank... so I can't really comment on whether I feel the diagnosis was correct.
Douglas


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## iluvmcr (Jan 14, 2005)

*Re: fuel gauge not working (copernicus0001)*

Thanks Douglas.
After I posted, I had the same experience. My fuel gauge reading went slowly to the correct level over 42 miles of driving. It was kind of interesting to watch the gauge slowly and steadily creep up over such a long period. I too thought the float (tank level sensing unit) was the problem.
The instrument cluster as an explination sounds a little strange. Please let me know if you think the diagnosis is correct after some driving (i.e. 3 months). Then I'll take my Phaeton in!


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## copernicus0001 (Nov 30, 2004)

*Re: fuel gauge not working (copernicus0001)*


_Quote, originally posted by *copernicus0001* »_
I had the identical problem... It would only happen occasionally (maybe 5 or 6 times over the period of a year) - and over a few days of driving the needle would slowly creep up to where it belonged and start functioning properly.
I thought it was a sticky float - and wasn't too bothered by it - at least not enough to have the car pulled apart. As I was taking the vehicle in for its 20k service last week, I stopped to fill the tank... and it happened again. So I had the dealer look at it while it was in for its routine service. After a number of tests, they came to the conclusion (with the aid of a technician in Auburn Hills) that there was a problem with a gear or some other internal component within the gauge in the dash. They replaced the instrument cluster (it is a single large component). The vehicle has not been driven enough since the repair to need to fill the gas tank... so I can't really comment on whether I feel the diagnosis was correct.
Douglas

I think their diagnosis was wrong... I finally filled the tank last night and the gauge stuck again. I intentionally let it run down to 1/8 of a tank in order to find out if the problem would reappear. In the past, this problem only arose if the tank had run a bit below 1/4 of a tank. This didn't guarantee precipitation of the problem, but I believe it was a necessary condition. I still think it is a sticky float assembly.
I usually don't let the gas run too low - and the problem doesn't show itself. Our gauge would correct itself in a similar fashion to your experience.... After driving on average of about 50 miles, the needle would eventually creep up to where it belonged and start functioning properly again. I think each time you hit a a bump in the road there would be enough impetus to allow the float to creep up slightly. Once it reached the fuel surface, the float, which may have been in a cocked position along a guide causing it to stick, is now free to assume its correct orientation and start functioning properly again.
I'll call the dealer this morning and let you know how things turn out.
Douglas


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## murphybaileysam (Dec 29, 2005)

*Re: fuel gauge not working (copernicus0001)*

The dealers usually don't keep much fuel in the cars. When someone buys one and the dealer fills the tank it still shows close to empty. The new owner starts driving and slowly sees the fuel gauge go up until it gets to Full. He can't believe what an engineering feat the Germans have mastered. The more you drive, the more gas you have in your tank!


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## car_guy (Aug 19, 2005)

*Re: fuel gauge not working (copernicus0001)*

Would checking the "Range remaining" in the MFI (small screen between Tach and Speedo) give you an idea if the sending unit was at fault? I assume that this is the same unit which feeds the computer to calculate the range as well as supplying the dash fuel gauge. Maybe someone could confirm that.


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## copernicus0001 (Nov 30, 2004)

*Re: fuel gauge not working (car_guy)*

The "Range Remaining" remains a small number when the gas gauge would stick... And it would grow as you drove around (as the gauge slowly crept upwards)....


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## car_guy (Aug 19, 2005)

*Re: fuel gauge not working (copernicus0001)*


_Quote, originally posted by *copernicus0001* »_The "Range Remaining" remains a small number when the gas gauge would stick... And it would grow as you drove around (as the gauge slowly crept upwards).... 

If the dealer knew this when the repair was done, they screwed up royally. If they didn't know this, they should have checked. Clearly, if the sender supplies both the gauge and the range indicator, and they both give erroneous information, then the problem does not lie with the gauge alone. 
DUH! How many thousands of dollars did this cost VW?


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (copernicus0001)*


_Quote, originally posted by *copernicus0001* »_The "Range Remaining" remains a small number when the gas gauge would stick... And it would grow as you drove around (as the gauge slowly crept upwards).... 

I'm not familiar with how the signals from the fuel tank level sensors are processed, or even where they are processed. However, I am going to guess that if 'range remaining' shows the same error that the fuel tank indicator needle shows, the problem is likely further upstream than the fuel gauge indicator needle.
The only information that I can add to this discussion is identification of some of the components that are used to measure fuel quantity. The picture below shows a Phaeton fuel tank that has been cut open to reveal the different components inside it.
The 'raw' indications from the three different level sensors in the fuel tank can be observed in Measured Value Block (MVB) Group 5 and 6 of the J285 Instrument Cluster Controller (controller 17). The values returned are as follows:
005,0,Fuel Sensors - Resistance in Ohms
005,1,Fuel Gauge,(G)
005,2,Fuel Level,Sensor 2 (G169)
005,3,Fuel Supply,Sensor 3 (G237)
005,4,Fuel Supply,Sensor 4 (G393)
;
006,0,Tank Contents (Individual Chambers in Litres)
006,1,Tank Content,(Total Contents - G),Display will be in Litres
006,2,Tank Content,(Left Side - G169),Display will be in Litres
006,3,Tank Content,(Right Side - G237),Display will be in Litres
006,4,Tank Content,(Reserve - G393),Display will be in Litres
Block 1 is the sum of the values returned by blocks 2, 3, and 4. Each of the lower lobes of the fuel tank has a sensor, and there is also a sensor in the upper area of the fuel tank.
If I was troubleshooting a problem like this, I would start by observing the values returned by the three sensors, and see if they made sense. If the readings returned by the sensors did not match the quantity of fuel known to be in the tank, and further investigation was needed, I would check the quality of the electrical connections to the sensors, and if necessary, pull the fuel gauge sensors out and have a look at them. Access to the sensors is from the trunk of the car (see photo below).
Michael
*Phaeton Fuel Tank Cutaway*

*Access to Fuel Tank Sensors*


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## dcowan699 (Nov 22, 2004)

*Re: fuel gauge not working (PanEuropean)*

I didn't want to start a whole new thread on this and I apologize for the sidetrack in conversation but when I saw that fuel tank "neck" in that picture Michael posted , it reminded of a situation that I've been wanting to ask about. 
I seem to have a problem with filling up my tank. It seems when I fully insert the nozzle into the opening and then fully squeeze the fuel nozzle handle, it seems that it too easily cuts the supply of fuel off as if the tank has just been topped off. I can't squeeze the lever more than half way otherwise it keeps shutting off the fuel supply. I've tried cheating by bringing the nozzle out of the hole about 1/3 of the way to prevent forward splashing but that doesn't help either. Does anyone else notice this??? On most all other cars I've owned, I pull the trigger all the way, set the prop hold into place at full speed and it shuts off once the tank is full. I can't seem to do this on the Phaeton. Is the crook in the neck of that tank too curved tricking the nozzle sensor into thinking the tank is full??? It's not a big problem. I'm just wondering if it's happening to anyone else because nothing can be done about it anyway.


_Modified by dcowan699 at 3:42 PM 2-6-2006_


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (dcowan699)*

Hi David:
I have not encountered any problems filling the tank, although I notice that once the pump shuts off, that's it - the gauge will indicate full and it is generally not possible to put any more fuel in the tank.
The only suggestion I can offer respecting the difficulties you are encountering is to try rotating the nozzle a bit. In other words, most fuel nozzles have a bit of a curve to them - try rotating the nozzle assembly perhaps 30° in each direction from 'normal' and see if that solves the problem.
Another consideration might be the flow rate of the fuel pump. In Canada, the maximum flow rate of a gas pump is governed by federal legislation, so we have the same standard all across the country. If the safety legislation for this kind of thing is handled at a state or city level in your country, you might just be using a fuel pump in a location that either does not regulate delivery rate, or has a very high flow rate permitted.
Michael


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## dcowan699 (Nov 22, 2004)

*Re: fuel gauge not working (PanEuropean)*

Thanks Michael. I think the rotation trick might just do it and you're right, there is a wide range of fuel rate delivery in the US nozzles. I've seen some so slow it would take 10 minutes or longer to fill 'er up.


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## Andrew C (Mar 29, 2005)

*Re: fuel gauge not working (dcowan699)*

Ooops I don't check the forum for a few days and miss my chance to help someone. 
We had the exact same problem with the fuel gauge "sticking". It happened when my wife stayed in the car with the key while I filled up the tank. The gauge slowly went back to almost full over the next few days but with every fill up it was sluggish to move up. I figured it was something mixed up with the electronics because I drove a little aggressively to slosh the fuel around and the gauge didn't move a bit. Also it happened after she remained in the car. Don't know if that really had anything to do with it but I could see how that could confuse the complex electronics.
I eventually decided to do a "hard reboot" by disconnecting both batteries. I waited overnight, reconnected the batteries and the next morning the gas gauge immediately went to full. Haven't had a problem for the last several months.
Don't think the gear thing sounds very plausible.


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (Andrew C)*

Hi Andrew:
Great to see you online again. Thanks for the advice about the fuel gauge. I do remember that the fuel gauge gave a funny reading once on my car (less than what was in the tank) - I just ignored it, the problem went away after about half an hour, and it has never recurred. I have no idea what caused it.
Will you be able to make it to the Chicago Get-Together this coming weekend? More information here: Chicago GTG in February. The most useful information is on page 3 and 4.
Michael


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## iluvmcr (Jan 14, 2005)

*Re: fuel gauge not working (car_guy)*


_Quote, originally posted by *car_guy* »_Would checking the "Range remaining" in the MFI (small screen between Tach and Speedo) give you an idea if the sending unit was at fault? I assume that this is the same unit which feeds the computer to calculate the range as well as supplying the dash fuel gauge. Maybe someone could confirm that.

That's exactly what happens. I had 70 miles range remaining and then filled the tank. After fillup, the range remaining still read 70 miles. Every few minutes I would check the range remaining and it would be increased.
Please keep in mind that my Phaeton had over 40,000 miles when this "problem" first occured. I drove the vehicle to 1/2 full and refilled it. The gauge and range remaining readings were normal.
Obviously this "problem" is very minor and will only be worth service repair if the gauge and miles remaining indication remained near empty/zero indefinitly.
Question: If the source of this malfunction does turn out to be the tank sensor, you might guess that a sticky float would function better after cleaning. Would it be safe to try a fuel treatment such as Gum Out or other fuel system cleaning product?

_Modified by iluvmcr at 12:06 AM 2-8-2006_


_Modified by iluvmcr at 12:07 AM 2-8-2006_


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (iluvmcr)*


_Quote, originally posted by *iluvmcr* »_Question: If the source of this malfunction does turn out to be the tank sensor, you might guess that a sticky float would function better after cleaning. Would it be safe to try a fuel treatment such as Gum Out or other fuel system cleaning product?

Personally, I'm kind of reluctant to make any kind of intervention in a system unless I have a fairly good idea of what the cause of the problem is. In the case of this particular glitch, we haven't enough experience or data to be able to support a hypothesis that attributes the cause of the problem to a specific component - so, for that reason, I think it might be best to just 'keep our powder dry' for a while.
Although the float devices could, in theory, be a cause of the problem, I think it is unlikely that two independent float sensors would both get stuck or give erroneous readings at the same time - which is what would have to take place to create a very low reading. Making an intervention (such as adding a chemical) at this stage of the game could just complicate matters later on. I guess I am saying we risk 'shotgunning' the problem if we make an intervention before we have a pretty solid theory about what is causing it.
Just my 2¢ - however, contrary arguments are welcomed.
Michael


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## Jack Orr (Mar 15, 2000)

*Re: fuel gauge not working (PanEuropean)*

And, in conclusion, I seem to recall that A6 2.7T's had a lot of fuel guage problems at first. It was blamed on the sulphur. The fix was replacement sensors in the tanks. (They had 3, as I recall)


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (Jack Orr)*

Ah, very interesting, thanks for mentioning that, Jack. It could be another one of these 'Chicago W12 winter fuel' issues.
On that topic - can someone remind me (before Friday), what brand of fuel is the safest to buy during the winter months in Chicago for a W12?
Michael


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## murphybaileysam (Dec 29, 2005)

All the winter blend 93 octanes should be fine from BP, Shell, or Mobil.
I see that they are starting to put a push on with ethanol. I don't know what octane it is and I wouldn't try it unless I was guaranteed by VW (or Bentley) that it was safe to use.


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## PanEuropean (Nov 3, 2001)

*Re: (murphybaileysam)*

Ah, you have not heard the stories about W12's and ethanol blends in the Chicago area - it seems you have to be very careful what you put in the W12 in the winter, due to heat retention within the engine compartment and fuel boiling. We had a huge discussion about this last winter, eventually, we pinned it down to regional fuel blending, not a problem with the Phaeton. Chicago is the only area that has this problem - perhaps it is an Illinois fuel standard.
One of the Chicago W12 owners identified one brand of fuel that was trouble-free, and posted the information here a few months ago. That was long before we thought of a Chicago GTG, so, I didn't take any note of it. However - at least three of us, myself, Brent, and David now need to know what the name of the troublefree brand is before we come to town.
The problem does not affect V8 engines, which dissipate heat much faster in the wintertime.
Michael


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## chrisj428 (Feb 26, 2005)

*Re: fuel gauge not working (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_On that topic - can someone remind me (before Friday), what brand of fuel is the safest to buy during the winter months in Chicago for a W12?

Amoco Ultimate would be my fuel of choice. After that, Shell V-Power. (Gotta love the Dutch)


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## PanEuropean (Nov 3, 2001)

*Re: fuel gauge not working (chrisj428)*

Thanks, Chris.
Michael


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## aaron843 (Oct 16, 2010)

*Fuel gauge slow to rise*

I just now noticed the same problem with my '05 V8. Filled up, and it showed only 1/4 tank. After ten minutes of driving it had slowly risen to 7/16 of a tank. The digital "range" indication coincides. I've scheduled an appointment with the dealer, they say that all they can do is hook a scanner up and see what codes are produced.


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## Zaphh (Jul 5, 2008)

Hi there,

There's an important point that I don't see mentioned in any of the posts: do you switch off the car when you refill it ?

If not, the fact that the gauge raises up very slowly is a functionality rather than a bug. What you see there is the smoothing algorithm in action, because without such functionality, if the sensor is situated at one end of the tank, if you turn right, you may see a full tank, while you may see an empty tank if you turn left...

So there is some sort of damping in order to integrate the fuel level in the tank, that would typically be done by software by having a sliding average over a long period (you accumulate and memorize measurements every second for 10 minutes, for instance = 600 values, and then, whenever a new value comes in, you add it divided by 600 and you substract the oldest value divided by 600). This would be a very sensible thing to do on something as variable as a fuel level sloshing in a moving car.

However, you must then understand that it will take ages (10 mn in the above case) to indicate the full level of a fuel tank after refill... unless you manage to tell the car that it should forget about trying to even out the measurements.

This may be done by switching the car off before you fill it up. Then, when it wakes up again, it takes a new measurement (no sloshing since the car is not moving) and starts its averaging again over a looong time.

If the car did not realise that you refilled, (because you kept the ignition on, for instance), it will average out the information of a full tank over a long time.


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## Bindaham (Apr 4, 2014)

PanEuropean said:


> The 'raw' indications from the three different level sensors in the fuel tank can be observed in Measured Value Block (MVB) Group 5 and 6 of the J285 Instrument Cluster Controller (controller 17). The values returned are as follows:
> 005,0,Fuel Sensors - Resistance in Ohms
> 005,1,Fuel Gauge,(G)
> 005,2,Fuel Level,Sensor 2 (G169)
> ...


*

Since I've changed my primary fuel pump and fixed the wiring of the sender, I noticed that my car starts losing power once the fuel gauge dips below half tank. Once full and prior to reaching half tank, the car is good. I changed the fuel filter way before the pump job.

Here's the mvb that I got when tge fuel gague was a little over half tank:

Address 17: Instruments (3D0 920 881 Q)

13:33:15 Group 005: Fuel Sensors - Resistance in Ohms
154 ohms Fuel Gauge (G)
86 ohms Fuel Level Sensor 2 (G169)
215 ohms Fuel Supply Sensor 3 (G237)
70 ohms Fuel Supply Sensor 4 (G393)


Address 17: Instruments (3D0 920 881 Q)

13:33:50 Group 006: Tank Contents (Individual Chambers in Litres)
0.0 l Tank Content (Main Chamber - G)
18.0 l Tank Content (Left Side - G169)
9.0 l Tank Content (Right Side - G237)
21.0 l Tank Content (Reserve - G393)


After an hour, I filled up with around 33 liters and measured again:

Address 17: Instruments (3D0 920 881 Q)

14:32:23

79.0 l Fuel Tank Total Contents
82 ohms Fuel Gauge (G)
79 ohms Fuel Level Sensor 2 (G169)
71 ohms Fuel Supply Sensor 3 (G237)
70 ohms Fuel Supply Sensor 4 (G393)

18.0 l Tank Content (Main Chamber - G)
20.0 l Tank Content (Left Side - G169)
20.0 l Tank Content (Right Side - G237)
21.0 l Tank Content (Reserve - G393)

Prior to half tank, the main chamber of the tank had 0.0 l and after the fill up close to full it had 18 l!

I never got a good understanding of the ohms reading, so if anyone can shed a light into these numbers I would appreciate it greatly.*


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## Harism (Jan 2, 2016)

My fuel gauge is not working either 
VCDS show one fault 

00439-Fuel Sensor 3 (G237)
010-Open or Short to Plus

Anybody know how i can fix this problem 
Thanks 

Sent from my SM-T350 using Tapatalk


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## nhdoc (Jun 18, 2010)

This thread has a couple of different issues but I will address the one where the gauge does not immediately return to full after refueling. 

It is important that these cars be turned off and the key removed before refueling so if you are refueling with the key in or engine on this will cause that. The gauge will not recover quickly if the ignition is left on during refueling. This is part of the "anti sloshing" buffering the gauge has built in to keep the reading consistent when going up and down hills and around corners. 

Now, I will say that my Audi has exhibited the same conditions as those described by some posts here even with the key out during refueling and there was a TSB in the mid 2000's that addressed this as a software issue in the cluster needing updating. It would occur only when the fuel level was allowed to go very low and then after refueling the gauge would be slow to recover. Eventually, after about 30-40 minutes of driving it would recover and that's just the "anti sloshing" feature at work. Not sure if this cluster problem was also in the Phaeton but thought I would pass this along to you. If you refuel and your gauge is slow to recover it means the sender is working right but the gauge isn't allowing the needle to quickly reset. Personally, I have just learned to live with this quirk but thought I would pass along my experiences.


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## invisiblewave (Sep 22, 2008)

Mine started doing that a couple of years ago, removing the key or refueling before the level gets too low has no bearing on it. I always remove my key for fueling, and I've tried filling it when it's 3/4 full, when it's half full, when it's running on fumes, etc, and there's no correlation to the problem occurring. It's been getting steadily worse on mine, going from intermittently bad to as it is now, intermittently ok. I have a feeling the anti-sloshing mechanism may be involved, though, because occasionally it will start working if I throw it round a few bends. I also suspect that there's a software gremlin at work, since leaving it standing with the ignition on sometimes causes the gauge to rise.

I should point out that the problem reported is different from the above, since mine doesn't throw any codes. There's a sender unit in the tank which is separate from the pump.


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## nhdoc (Jun 18, 2010)

Harism said:


> My fuel gauge is not working either
> VCDS show one fault
> 
> 00439-Fuel Sensor 3 (G237)
> ...


The fuel level sender is in the tank and it sounds like it needs to be replaced. It is not that uncommon - my old Phaeton had both replaced in its history. There are DIY directions on some of the Audi boards which should be very similar if you google "G237 level sender" you will find them.


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## nhdoc (Jun 18, 2010)

invisiblewave said:


> Mine started doing that a couple of years ago, removing the key or refueling before the level gets too low has no bearing on it. I always remove my key for fueling, and I've tried filling it when it's 3/4 full, when it's half full, when it's running on fumes, etc, and there's no correlation to the problem occurring. It's been getting steadily worse on mine, going from intermittently bad to as it is now, intermittently ok. I have a feeling the anti-sloshing mechanism may be involved, though, because occasionally it will start working if I throw it round a few bends. I also suspect that there's a software gremlin at work, since leaving it standing with the ignition on sometimes causes the gauge to rise.
> 
> I should point out that the problem reported is different from the above, since mine doesn't throw any codes. There's a sender unit in the tank which is separate from the pump.


I just read on some of the Audi forums that pulling the fuses for the fuel pumps and instrument cluster and turning the key on (not to start or run, just on) and then turn off, replace fuses and that fixes it. I will try it in my Audi the next time I refuel if it does the slow recovery thing. Might be worth a shot in your situation too.


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## Jim_CT (Jan 25, 2006)

*Fuel Gauge reads 75-80%, although tank is 100% full*

I had this problem for a year or so. However, lately the fuel gauge has been reading properly, but unfortunately I can't say what caused it to work again. I recently ran the tank completely dry (a stupid mistake) and I have also been using a fuel additive every thousand miles or so. I wonder if a piece of dirt or some other material was interfering with fuel sensor operation, and in time, it became dislodged.

I had narrowed it down to fuel sensor G169 - its readings were anomalous with the other sensors when the tank was full. As I am the only one that drives the car, and the only disadvantage was the tank read low until the volume dropped below the indicated amount, it wasn't a big deal.

Jim


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