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Faulty fuel gauge FIX (worked for me)

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44K views 41 replies 20 participants last post by  HattieBrooks  
D
#1 ·
Thought id post what i did to sort my fuel gauge out, when i brought the car about 6 weeks ago i noticed the day after the fuel gauge was not working correctly so after some searching the net i found the fuel gauge fault fell into 2 categories 1st where temp and fuel gauge move around at random a lot and the centre screen plays up and the 2nd where peoples fuel gauge and only the fuel gauge seems to just be out of sync where at empty it sits just under half and full shoots right off the top mine was like the 2nd type my fuel gauge was out of sync.

1st thing i did was remove the dash pod from the car but left it plugged in just pulled it forward enough to remove the front cover by removing the small torx screws once it was removed i gently pulled the needle off and then re positioned it ( i did this in the car park at the petrol station after filling up to the brim) at full then switched the ignition on and off few times, seemed ok but the more i turned it on and off the further round the needle shot until after a bout 10 times it was showing about quarter of a tank past full again.

This got me thinking and i noticed when you turn it on the needle shots round to full and you can here it hitting a stop of some sort and i thought maybe its this that is throwing it out moving it each time it hits so i pulled off the needle again turned the needle round and there is a little tab which i removed then reset the dial to full again by switching the ignition on and i know its full so just repositioned the needle at the full mark now when i switched the ignition on and the needle shots round it no longer hits a stop but when turning off the needle shots back and hits a clear piece of plastic that the full beam light shines through so i had to take a nick out of that too now turning the ignition on and off the needle hits nothing and as a result was staying accurate every time.

I then needed to modify the front cover too as the cylinder part that fits down round the gauge the walls would get in the way of the needle so the needle would hit the sides and knock it out again so i trimmed with a sharp knife both sides where it goes to empty and full so the needle can shot past the wall of the cylinder with no restrictions i then reassembled it that was 5 weeks ago and its been spot on since.

If you look at your fuel and temp gauge when you turn the ignition on the temp gauge moves to the start then moves to where the temp is but slowly and in a controlled manner and the fuel gauge moves to the start and the shots very quickly to where it sits but it goes so fast it over shots and springs back so I'm guessing it should be dampened like the temp gauge and as a result of it moving so quick and banging into its stop this is what is throwing it out of whack so by removing the stops it no longer bangs into anything and stays accurate.

Heres some pics i never took any while doing the job but heres some to show roughly what i did:

This shows how the gauge sits when the dash is in sleep mode:
Image


This shows the needle with the dash off resting out side the gauge:
Image


If you look closely you can see where i trimmed the back of the fascia so the needle can move behind it:
Image


And the same off the other side:
Image


Here's a link to a vid i made to show how the difference in the speed of the 2 needles(temp and fuel) and if you watch very carefully you can see it shot past where its meant to sit the spring back before i modified it you could here it hit the side of the fascia and now it shots out the gauge off the top and springs back to where it should be sitting, its hard to see because it moves so fast but if you look close;y enough you will see it:


Hopefully Ive explained it well enough but if there is any confusion let me know and ill try and explain it better, as i said this has permanently fixed mine and cost nothing but my dash was in full working order everything else is working perfectly it was just my fuel gauge sitting 1/2 a tank out, i dont think this will work for the people that are suffering pod failure where the gauges do there own thing and the centre screen packs up.
 
#2 ·
After reading this is seems to be a possibile resolution. I questioned why my fuel gauage randomly gained the error also and noticed the stop and start points a little odd also.

How is it going with this, another month on?
 
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#4 ·
In that case, wouldnt mind giving this a try.
Whats the risk involved exactly? I see you managed to do it all in a petrol station car park :eek:

This might sound very strange but my fuel gage only started playing up after I started filling up on full tanks :? . Ive not run it down to empty yet. Its probably got nothing to do with the gauge problem, but it did have me wondering...
 
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D
#5 ·
Sh0x said:
In that case, wouldnt mind giving this a try.
Whats the risk involved exactly? I see you managed to do it all in a petrol station car park :eek:

This might sound very strange but my fuel gauge only started playing up after I started filling up on full tanks :? . Ive not run it down to empty yet. Its probably got nothing to do with the gauge problem, but it did have me wondering...
Click to expand...
Well mine only moved when filling the tank right up, if you listen when you switch the ignition on when you have a full tank the needle shoots across and you can hear it hit a stop and its this that seems to move the needle if you compare the speed the fuel gauge needle moves compared to the temp gauge when you switch the ignition on its a lot faster and I'm guessing the fuel gauge needle should move slower like the temp, so when you send the dash off to the companies to repair they replace the fuel gauge motor to solve the problem with a new motor like one of these:

http://cgi.ebay.co.uk/Audi-TT-Jaeger-Sp ... 45fabea2fe

but by doing what i have done and resetting the needle once you have filled the tank right up (which is why i did it at the petrol station) solves this problem 100%.

Its dead easy to do, you dont even need to remove the dash pod just release it from the dash pull it forward leaving the wire connections connected remove the tiny Torx screws that hold the front screen on from behind this gives you access to the needle and you just gently pull the needle off (not difficult) trim the little flap off at the bottom of the needle then trim the pod front like i show in the pics so the needle can shot round and not hit the insides of the display, then refit the needle at the full mark (once filled up to the brim) with the ignition on that way its calibrated then refit everything in reverse order.

One thing that would confirm you have the same problem as mine if you used the miles till empty on the info screen which remains accurate even when the gauge reads wrong if you were to run it down using this your gauge would read half full when you have very few miles left till empty on info screen.

doing this repair sounds complicated but it really isn't if you drop me a PM if you need anymore info i will forward on to you my phone number and i can explain it better.
 
#11 ·
dpbayly said:
Sh0x said:
In that case, wouldnt mind giving this a try.
Whats the risk involved exactly? I see you managed to do it all in a petrol station car park :eek:

This might sound very strange but my fuel gauge only started playing up after I started filling up on full tanks :? . Ive not run it down to empty yet. Its probably got nothing to do with the gauge problem, but it did have me wondering...
Click to expand...
Well mine only moved when filling the tank right up, if you listen when you switch the ignition on when you have a full tank the needle shoots across and you can hear it hit a stop and its this that seems to move the needle if you compare the speed the fuel gauge needle moves compared to the temp gauge when you switch the ignition on its a lot faster and I'm guessing the fuel gauge needle should move slower like the temp, so when you send the dash off to the companies to repair they replace the fuel gauge motor to solve the problem with a new motor like one of these:

http://cgi.ebay.co.uk/Audi-TT-Jaeger-Sp ... 45fabea2fe

but by doing what i have done and resetting the needle once you have filled the tank right up (which is why i did it at the petrol station) solves this problem 100%.

Its dead easy to do, you dont even need to remove the dash pod just release it from the dash pull it forward leaving the wire connections connected remove the tiny Torx screws that hold the front screen on from behind this gives you access to the needle and you just gently pull the needle off (not difficult) trim the little flap off at the bottom of the needle then trim the pod front like i show in the pics so the needle can shot round and not hit the insides of the display, then refit the needle at the full mark (once filled up to the brim) with the ignition on that way its calibrated then refit everything in reverse order.

One thing that would confirm you have the same problem as mine if you used the miles till empty on the info screen which remains accurate even when the gauge reads wrong if you were to run it down using this your gauge would read half full when you have very few miles left till empty on info screen.

doing this repair sounds complicated but it really isn't if you drop me a PM if you need anymore info i will forward on to you my phone number and i can explain it better.
Click to expand...
Great information there. I have the same problem confirmed by the range till empty vs fuel gauge reading.
Im going to read through and have a look at the dashpod itself to consider if Im able to take this on.

Good write up :wink:
 
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#16 ·
Wow! I'm impressed with your mechanical dexterity and perseverence in solving this issue.

The issue isn't nececerily a mechanical one with motors going out of spec however.

This issue is sometimes due to FLASH memory corruption in the dashpod which corrupts the stored offset value for the fuel gauge causing its zero value to typically be about half way. the offset is meant to be a fine trim to compensate for small sensor variations etc.

The offset value can be adjusted using Vag-Com, which is worth a try but this attempt usually fails because it's actually the memory address that's become corrupt and the programme uses some odd code value that is wildly out - hense why it shoots over.

When the first dashpods were made they used electrically programmable on chip processor memory (FLASH). If this type of memory is programmed too quickly the stored charge in the memory cells is weak. This works fine for a while but after a few years, and especially at extremes of temperature, the first signs of corruption can show up.

Symptoms have commonly been gauge offset problems but often, DIS display going bright, jumping needles where the processor continually crashes on startup until it warms up and even strange artifacts appearing on the DIS display where the stored bitmap symbol /background image is the thing suffering from corruption.

One fix was to add a heater on the back of the chip to warm it a little before starting. This typically gave it a year or two extra life but the problem is a deteriorating one.

Later dashpods had "mask programmed" devices from about 2004 which didn't suffer from this problem as the programme code was hard wired during chip fabrication. It was those that Audi were eventually free issuing as a warranty repair following the BBC Watchdog publicity although the first ones they swapped in were probably the FLASH types as they were unaware of the cause. Some people have had a series of early replacement dashpods. After a while they stopped replacing them for all but full service history customers, thinking that all the faulty ones were now replaced - but a few have slipped through the net.

I hope your mechanical fix, which is basically compensating for an incorrect offset, lasts the course and the corruption does not spread. Its certainly worth a try as it's a cheap fix but you may eventually need to gry the root cause seen to.

If it's a failed coil in the motor then a more complete fix may be to change the motor/meter movement.
 
D
#17 ·
John-H said:
Wow! I'm impressed with your mechanical dexterity and perseverence in solving this issue.

The issue isn't nececerily a mechanical one with motors going out of spec however.

This issue is sometimes due to FLASH memory corruption in the dashpod which corrupts the stored offset value for the fuel gauge causing its zero value to typically be about half way. the offset is meant to be a fine trim to compensate for small sensor variations etc.

The offset value can be adjusted using Vag-Com, which is worth a try but this attempt usually fails because it's actually the memory address that's become corrupt and the programme uses some odd code value that is wildly out - hense why it shoots over.

When the first dashpods were made they used electrically programmable on chip processor memory (FLASH). If this type of memory is programmed too quickly the stored charge in the memory cells is weak. This works fine for a while but after a few years, and especially at extremes of temperature, the first signs of corruption can show up.

Symptoms have commonly been gauge offset problems but often, DIS display going bright, jumping needles where the processor continually crashes on startup until it warms up and even strange artifacts appearing on the DIS display where the stored bitmap symbol /background image is the thing suffering from corruption.

One fix was to add a heater on the back of the chip to warm it a little before starting. This typically gave it a year or two extra life but the problem is a deteriorating one.

Later dashpods had "mask programmed" devices from about 2004 which didn't suffer from this problem as the programme code was hard wired during chip fabrication. It was those that Audi were eventually free issuing as a warranty repair following the BBC Watchdog publicity although the first ones they swapped in were probably the FLASH types as they were unaware of the cause. Some people have had a series of early replacement dashpods. After a while they stopped replacing them for all but full service history customers, thinking that all the faulty ones were now replaced - but a few have slipped through the net.

I hope your mechanical fix, which is basically compensating for an incorrect offset, lasts the course and the corruption does not spread. Its certainly worth a try as it's a cheap fix but you may eventually need to gry the root cause seen to.

If it's a failed coil in the motor then a more complete fix may be to change the motor/meter movement.quote]

I see what your saying and not disputing it but with mine when i first looked at it (at the petrol station) i simply filled it right up so i knew it was full then dismantled the dash pod removed the face cover so all the gauges and needles are accessible and removed the needle and simply repositioned it, i then cycled the ignition a few times and all seemed good the needle returned to full every time, i then refitted the dash face and then cycled the ignition again and i could hear the needle hitting the side of the dash the bit that surrounds the gauge and each time i cycled the ignition the needle would hit and move further round each time and after about 10 turns it was reading about quarter of a tank PAST full again.

So thats when i took it apart again and trimmed the dash about so that when i switched the ignition on the needle shot round but hit nothing and its been spot on ever since and i fill up to the brim every Friday and its been perfect. :p

If you watch my vid in my post you can see a difference in the speed the needle for the temp and fuel it's very different the temp needle seems dampened and the fuel one not this is what I'm guessing is the problem in my case and my symptoms were the same my gauge reading half full when i was actually empty and the rest of my dash pod worked perfectly.
Click to expand...
 
#18 ·
Some owners have had their dealer fix a needle offset issue with diagnostic software. I tried it on a faulty dashpod without success - it stored the value but didn't act upon it. I also tried it on a working dashpod and was able to move the needle offset successfully - I put it back again of course :wink:

Looking at your video I wonder if one of the meter coils has failed? There's not much to them. There's a permanent magnet on the spindle and two coils at an angle. By varying the current in each coil you can effectively rotate the magnetic field through a little over 90 degrees - the magnet just aligns itself with the balance point of the field. There's no return spring just gravity pulling the needle back down when the power is removed.

If one coil has gone open circuit or has shorted turns your balance point will be lost and you'll have one coil pulling against gravity and a weak coil instead of a full strength coil - so that would probably hammer over. You've moved the needle relative to the magnet to correct the offset and I'm also wondering if the banging of the needle has caused it to slip on the shaft progressively, giving you a gradual change in rest position, until you stopped it banging.

If that's the case and a coil has gone then the situation may not deteriorate although the reading may not be as linear as it should be. You could always get a second hand pod for another movement if this is the issue.
 
B
#19 ·
Maybe I am a little late with this thread but after I disassembled my dashpod having the same problem described by dpbayly I can confirm that the problem comes from the needle (coil) motor, in particular from slipping shaft on the permanent magnet (as mentioned somewhere in the John-H's last post). I can also confirm that the needle motor cannot be opened because the wire coils are wound after the magnet is inserted there so I cannot re-glue the shaft to the magnet and the only solutions for now are the "cutting" solution described by dpbayly (which I think that it will be temporarily but may last a little longer than without this "cutting" which makes the needle look defective and ugly when off) and buying new needle motors. Maybe (as an option) we can check the local scrapyard for removed defective Audi dashpods (from A3, A4 or A6) and get some needle motors! ;)

[Edit]

In the meantime I got an idea... if the fuel gauge needle motor has a slipping shaft... maybe the temp gauge motor is still in good condition so I will try to swap them next time I open the dashpod and post the results.
 
D
#21 ·
Great thread, I think I will have to give this a try.

Funny enough like someone mentioned earlier this only started to happen when I began completely filling the Fuel tank every couple of weeks. The TT is used as a daily commuter now.

I also noticed the sound of the needle hitting the inside of the dashpod :?

You can see the problem with my Fuel Gauge needle below:
viewtopic.php?f=2&t=315291
 
T
#22 ·
Well dpbayly

Thank you very much. I had the same problem of over reading half a tank and the needle hitting the side of the gauge

I read the posts several times gathered some courage and tried this.

As the man says it works! Just take your time and de assemble the clock fascia completely ie take the glass out and you are good to go. I used a pair of pliers to remove about 5mm of trim, and then sanded it down, after a few trial fits and adjusting got it to the right shape to allow the needle free movement.

A week later and still ok.

Top man. :D :lol:
 
M
#23 ·
I had a go at doing this today, however I was unable to remove the needle? Even with a decent bit of force it wouldn't come off?

I could pull it and turn it and it would adjust the reading to full but turning the ignition off and on several times you could very slowly see it going further round.

I gave up in the end and put it back together without taking a bit out of the cylinder which was a big mistake as after 2-3 turns of the ignition it went way out again, so I should of still done that step as it may of taken a lot longer to go back out.

Will have another go at it on Friday, but any advice on removing that needle would be appreciated.

Martyn.
 
T
#24 ·
mrmartyn1984 said:
I had a go at doing this today, however I was unable to remove the needle? Even with a decent bit of force it wouldn't come off?

I could pull it and turn it and it would adjust the reading to full but turning the ignition off and on several times you could very slowly see it going further round.

I gave up in the end and put it back together without taking a bit out of the cylinder which was a big mistake as after 2-3 turns of the ignition it went way out again, so I should of still done that step as it may of taken a lot longer to go back out.

Will have another go at it on Friday, but any advice on removing that needle would be appreciated.

Martyn.
Click to expand...
Same here my needle won't come off at all, even tried gentle force under it with a screwdriver but it didn't move. Must of been glued on in its past.

I did start moving the needle though gently between full and empty to see if returns to same position on its own (fully unplugged out of the car). At first it slowly fell back to the same start empty position then it stopped returning all together and I thought I'd broken it so I plugged the cables back in, turned on ignition and it instantly went back to how it was when I started.
I then unplugged the cables again and this time moved the needle too far left, way past empty (same position of the final settled point on youtube clip). When I did this the needle made a horrible click sound and assumed I def now broken it but to my surprise when I plugged it back in not only did the needle now go to the correct position, it now seems exactly the correct position and calibrated like new.
Have only just done this so will update in few weeks on how it turned out.
 
T
#25 ·
Ok the temp fix of manually moving the fuel needle didn't last, 2 days later and its back to its old self (ie full is way past F mark and empty is just under half a tank)
Got me thinking... As my needle doesn't slin independently of its axis but rather is glued on to the shaft of the motor, then there must be a way to reset / tweak, calibrate this with a laptop plugged in to the car computer. Can anyone point me to a thread or user that has dabbled with calibrating instruments via laptop? Cheers guys.
 
J
#26 ·
I've just done this procedure on mine following OPs advice, seems to be working at the minute, will update as time goes on - have to say however, there was much 'how the bloody hell did he do this in a petrol station' or words to that effect, but in all took me about 1hr, mostly getting the bottom dash section to fit back in place!

Nice one OP!
 
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