# Tank Malfunction & Fuel Gauge Stuck on Empty



## jaydee77 (Feb 20, 2021)

Hi There,

I have this weird problem with my audi TTS 8J. It all started one day when i started the car (after cold snow weather) and my dash language was reset to default (prob. low battery). I had the Tank malfunction error, An error with the ambient temp. sensore giving wrong readings and my fual gauge stuck on empty while im sure the tank was half full.

Scanning the fault codes showed an error on Fuel Sender 2 (it's a Quattro). I also observed that the temp sensore was giving wrong values to the dash and sometime there was no reading at all (just a black part on the HUD). When there is no reading then the dashboard light from suspension would turn on. When the faulty readings got back the suspension light would clear.

Now we are searching to pinpoint the problem. We took the audi repair manuals to check on the fuel sender units. It said the following
- Connect multimeter (resistance test) between contacts -2- and-3-.
With Fuel gauge sender -G- installed:• 
Sender at lower stop: approx. 270 Ω.• 
Sender at upper stop: approx. 70 Ω.

- Connect multimeter (resistance test) between contacts -1- and-2-.
With fuel gauge sender 2 -G169- installed:• 
Sender at lower stop: approx. 270 Ω.• 
Sender at upper stop: approx. 70 Ω.

Resistance would be 270 ohms if tank would be empty (lower position) and resistance would be 70 ohms if tank would be full (high position). We checked on both G1 (fuel sender 1) and G165 (fuel sender 2). Tank was 3 quarter full and G1 gave us 60 Ohms and G165 gave us 200 Ohms... so our guess is that fuel sender 2 is really broken...

But we also checked the voltage on the cable (coming from the dash unit).... both left and right side measure 0.4 voltage on the signal cable from the dash....

Also the ambient temp.sensor shows weird rating like -20Celcius when its +10... those values can change after we turn off the engine and restart it... i have see -8, -20 and also -32... the dash is receiving values but incorrect ones...

So we r trying to figure whats wrong:
1. Temp. sensor broken ? 
2. Fuel sender 2 broken ?
3. A dash problem ?
4. Something else ? electrical ?

but i would have expected a fault code then.... maybe u guys can point me in the right directions


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## SwissJetPilot (Apr 27, 2014)

Which fault code came up? 
Did you use a generic code reader or VAG specific like VCDS or OBDeleven?

It would be worth doing a Google search; "Ross Tech xxxxx" where xxxxx is the fault code. They provide possible causes and solutions which may help resolve this issue.

If you need any additional workshop manuals, we have an assortment you can download -

*FAQ - Audi TT (8J) Workshop Manuals & Self Study Programs*
https://www.ttforum.co.uk/forum/viewtop ... &t=1833829


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## jaydee77 (Feb 20, 2021)

Thank you for your reply

Unfortunately i don't have VCDS but a generic scantool.

Fault 00438 Fuel Supply Sensor 2 (G169).
Fault 00779 Outside Air Temperature Sensor (G17)

We have the complete workbooks from audi, thats where i got the fuel sender Ohm check from...

But the main reason i ask here because i want to check which is more likely:
- Both parts being defective ?

Or

- A Instrument cluster failure ? / electrical problem ? 
The weird thing is that we dont measure 5v/12v on the connectors of sender 1 & 2... but maybe thats normal when there's this error in de intrument cluster


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## FNChaos (Nov 30, 2016)

What resistance value do you get on G pins 3 & 4 ?
What resistance value do you get on G169 pins 2 & 3 ?


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## jaydee77 (Feb 20, 2021)

Hi

On G we disconnected the connector and mesaured 60 Ohms

On G169 we disconnected the connector and measured 200 Ohms

PS on G169 you measure pin 1 & 2 right (not 2&3)


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## IPG3.6 (Sep 5, 2015)

Outside air temp has nothing to do with your fuel level read out so don't worry about that one for now.

It's going to be your sender and also the coding of the cluster since it looks to also have been reset by the cold. So check those two things.


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> Hi
> 
> On G we disconnected the connector and mesaured 60 Ohms
> 
> ...


The measurements requested above are across the the potentiometer, not the wiper arm.
Readings should be ~340 ohms. Are you sure you are on the right pins?


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## jaydee77 (Feb 20, 2021)

IPG3.6 said:


> Outside air temp has nothing to do with your fuel level read out so don't worry about that one for now.
> 
> It's going to be your sender and also the coding of the cluster since it looks to also have been reset by the cold. So check those two things.


Thanks for your reply.... yeah we still in doubt between cluster & fuel sender 2....

Is it possible the coding changed becaue the car got a reset during the cold days ? It was working before.... I think this must be done with VCDS right ? Any directions on what coding this should be (so we can check) ?


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > Hi
> ...


Mmmz this is what the workbook says:
- Connect multimeter (resistance test) between contacts -1- and-2-.
With fuel gauge sender 2 -G169- installed:• 
Sender at lower stop: approx. 270 Ω.• 
Sender at upper stop: approx. 70 Ω

But i also seee this :

- Connect multimeter (resistance test) between contacts -2- and-3-.
With fuel gauge sender 2 -G169- installed or removed:• 
Sender in any position: approx. 340 Ω.

So we checked only pin 1&2 while the sender is in the fuel tank with the connector disconnected


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## SwissJetPilot (Apr 27, 2014)

Is this the reference to which you are referring?

Page 34, Workshop Manual - _*Fuel Supply System, Petrol Engines A005TT01020*_

Older post on this topic -

*Fuel gauge not working*
https://www.ttforum.co.uk/forum/viewtop ... &t=1929627


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## jaydee77 (Feb 20, 2021)

Hi

Thats the Reference for G (Fuel sender 1)....

I have a Quattro and that one has another Fuel Sender G169 (Fuel sender 2)

In the above i referenced the part for G169 which has a 3 pin connector

PS: thanks for all your quick replies.


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## FNChaos (Nov 30, 2016)

Measuring the total resistance of the potentiometer from sender G169 pins 2 & 3 (end to end ) should be ~340 ohms. 
You've measured the wiper arm (pin1) to one end of the pot (pin2) and you say you read 200 ohms. Logic dictates that if you measured the wiper arm (pin1) to the other end of the pot (pin 3) you should see ~140 ohms (200 +140 = 340)

If all that works out it means your pot is good but the float arm is stuck for some reason. If you don't get these values it means the sender is bad or you are measuring the wrong pins.


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> Measuring the total resistance of the potentiometer from sender G169 pins 2 & 3 (end to end ) should be ~340 ohms.
> You've measured the wiper arm (pin1) to one end of the pot (pin2) and you say you read 200 ohms. Logic dictates that if you measured the wiper arm (pin1) to the other end of the pot (pin 3) you should see ~140 ohms (200 +140 = 340)
> 
> If all that works out it means your pot is good but the float arm is stuck for some reason. If you don't get these values it means the sender is bad or you are measuring the wrong pins.


Thanks FNChaos... gonna re-measure the sender with your information and ill post back on it.


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> Thanks FNChaos... gonna re-measure the sender with your information and ill post back on it.


You can also apply this same test to G.
Pins 3 & 4 = 340 ohms
Pins 2 & 3 = 60 ohms (according to your testing)
Pins 2 & 4 should then equal ~280 ohms


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > Thanks FNChaos... gonna re-measure the sender with your information and ill post back on it.
> ...


Will do Thanks !

PS: can u explain while G measure 60 Ohms and G169 measures 200Ohms ? I mean the tank is 3 quarters full so i expected 60 on both? but maybe my whole thinking is wrong because i still dont understand the system exactly.


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Is this the reference to which you are referring?
> 
> Page 34, Workshop Manual - Fuel Supply System, Petrol Engines A005TT01020
> 
> ...


Mmmz Swiss... interesting topic... that guy has almost the same problemn i have. Fuel Gauge not working and also bad temperature reading in dash (he has -13)....

Gonna try hoggy's suggestion leaving the battery negative off, ignition on then off ... wait for 30 minutes then reconnect


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> PS: can u explain while G measure 60 Ohms and G169 measures 200Ohms ? I mean the tank is 3 quarters full so i expected 60 on both? but maybe my whole thinking is wrong because i still dont understand the system exactly.


Assuming the senders are linear and not logarithmic, I would expect a value of ~120 ohms from each at 3/4 full?

I did find a drawing that indicates that the senders are wired in series (which surprised me). I was thinking a secondary sender G169 would be used as a 'sanity' check to ensure that G was accurate, but series-wired means they both need to be functional for your fuel gauge to work









As you previously noted, only Quattro models have two senders. I read somewhere that mis-programming your vehicle as a FWD causes sender G169 not to be recognized. (probably doesn't apply to you, but if you recently had your ECU flashed maybe?..)

The next drawing shows the fuel floats for each sender. The wire arm attached to the float cause the potentiometer to vary its resistance as the float rises and the arm rotates. If one of the arm is stuck / bound-up your resistance readings would be off








If necessary, pulling the sending units shouldn't be too big of a deal (open your gas cap first to relieve pressure, open doors / windows to vent, lots of rags to catch drips and of course no smoking or electrical anything nearby) That said, I wouldn't do it unless I had new gaskets to reseal.


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## SwissJetPilot (Apr 27, 2014)

I found this Youtube for a VW Golf 5 which shows how the VCDS is used. Not sure if this will help but figured I'd bring it up just in case. 

As already know, a fault code is generated when the reported value is outside the expected range. In this image, the *Fuel Sender Resistance* is *233 ohms*. When you mouse over these data fields a small 'bubble' will appear with the expected range. Unfortunately it's not shown in this video. But for the sake of argument, if the expected range is 100 to 300 ohms and VCDS reports <100 or >300, a fault will be generated.

Now if you decide to replace the fuel level sender or remove it and clean it, you will need to perform an Adaptation after you reinstall it. Generally speaking, an Adaptation should be done anytime you replace an electronic device which has a variable output or potentiometer; e.g. throttle body, fuel level sensor, HVAC vent servo, gas pedal, roof flap servo, etc.

Since even identical devices can have a slightly different range, the VCDS Adaptation interrogates it to figure out the new min and max values of that device and those values become the new expected range. Same goes if you clean up the contacts and reinstall the exact same part. This is why you can't just install a new or reconditioned part and clear the fault.

A VCDS will let you test the device and see what's going on and gives you the ability run the Adaptation when the part is reconditioned or replaced so the vehicle 'learns' the new expected range. After the Adaptation, you can then clear all the faults and everything will be back to normal.














As an FYI, a VCDS scan would provide a fault list that would look like this. In this particular example, further investigation found a literal rats nest as the cause. Which is why you should never do a CAT delete! :lol:

_Address 17: Instruments Labels: 1K0-920-xxx-17.lbl
Part No SW: 1K6 920 974 D HW: 1K6 920 974 D
Component: KOMBIINSTRUMENT VDD 1216 
Revision: V0002000 Serial number: VWX7Z0G83NA8RZ
Coding: 0007203
Shop #: WSC 01052 444 68459
VCID: 356173AF5C2628898D9-8060

1 Fault Found:
00438 - Fuel Supply Sensor 2 (G169) 
010 - Open or Short to Plus
Freeze Frame:
Fault Status: 01101010
Fault Priority: 2
Fault Frequency: 1
Reset counter: 99
Mileage: 179012 km
Time Indication: 0
Date: 2000.00.00
Time: 17:20:01_


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## SwissJetPilot (Apr 27, 2014)

Looks like the Fuel Level Sensor is available as an individual replacement component and is also covered in the WSM a few pages on.

On the *ESC Tuning* website it's listed as PN 1K0919673K but you should verify this if this is the correct part. Unfortunately the published parts list isn't exactly helpful.

Bit more looking and it seems to be manufactured by Vemo, as shown on this UK parts website.


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Looks like the Fuel Level Sensor is available as an individual replacement component and is also covered in the WSM a few pages on.
> 
> On ESC Tuning it's listed as PN 1K0919673K but you should verify this if this is the correct part. Unfortunately the published parts list isn't exactly helpful -
> 
> ...


Hi ! Thanx for your follow-up.... The individual part is for the G sensor. The G169 is nr 26 on the etka drawing. So its inclkuded in the suction pump....

You guys are very helpfull. In my next post i write a follow up because i tested with VCDS today


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## jaydee77 (Feb 20, 2021)

So just a quick follow UP.

Hooked the car up on VCDS and this is the main error (sorry its in dutch):
00438 - Vlotter 2 G169
010 - Onderbreking/kortsluiting met plus
Bevries Frame:
Fout Status: 01101010
Fout Prioriteit: 7
Fout Frekwentie: 1
Reset teller: 93
Kilometrage: 110110 km
Tijd Indicatie: 0
Datum: 2021.02.20
Tijd: 16:03:04

The coding of the instrument panel is:
0065008

0064 is when you have magnetic ride installed (i have this). And fuels sender 2 is +0001 so the 0065 looks OK to me

I did an output test on the analogue needles. All needles were OK

Now in adaptation of the instrument panel i tried looking at Fuel sender 1 and 2. Default value is there 128 but both gave no readings in adaptation (NA) ... i suspect this is because the tank malfunction error is in there and cant be cleared.

Now next i've done an Advanced Measure Block readout. In the attachment it shows the measured values.

So what u guys think of that ? Am I right to say that fuel lever 2 sender is really dead (G165) and fuel sender 1 is OK (G) ??


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## SwissJetPilot (Apr 27, 2014)

Since you have a VCDS, you should be able to check the measurement blocks (shown in the video clip image). They will be under Address 71 - Instruments. As mentioned previously, if you put the mouse over the value, the expected range bubble will appear.

Since the data displayed is live, if you shake the car hard enough to get the fuel to slosh around a bit and can actually move the float, it should display a change in value.

And you're right, as long as you have an existing fault, you can't run an Adaptation.

Here's my software code; your codes will be different, but yours should include +0001 for AWD and +0064 for MRS


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## SwissJetPilot (Apr 27, 2014)

Unfortunately I don't have any screen shots of the Instrument Measurement Blocks, but I do have this one from the Roof just to show you what they look like.

It will display three blocks at a time. Just change the *Group* number to go through them all. You'll eventually get a message that data isn't available which means that's all there are. In this case, there were only eight groups.

You can sort which Group is displayed and organize them any way you want. For example you can display Group 001, 003, 005 or Group 002, 001, 007.

Either click on the *Up / Dn* button or enter the number manually.


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Since you have a VCDS, you should be able to check the measurement blocks (shown in the video clip image). They will be under Address 71 - Instruments. As mentioned previously, if you put the mouse over the value, the expected range bubble will appear.
> 
> Since the data displayed is live, if you shake the car hard enough to get the fuel to slosh around a bit and can actually move the float, it should display a change in value.
> 
> ...


Yes thats exactly what i tried today !!!..

My coding is 0065 so that means Magnetic ride PLUS fuel sender 2 so thats correct !!

Both adaptation on sender 1 & 2 i have checked but they both give NA. As said before i suspect it doesnt give values there because the fault is there and won't clear.

So i checked the advanced measurement blocks (my previous screenshot). And thats where i got the correct reading from sender 1 and no reading at 2...

SO yeah i really think sender 2 is dead  Just want to make sure hehehehe

There's nothing more annoying then spending cash on parts and the problem is somewhere else


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## SwissJetPilot (Apr 27, 2014)

Looks like you've nailed it and proven out yet again the value of a VCDS. 

The only other thing you might try is to swap both sensors and run the test again. If 2 failed the first time, when you swap it, you should expect 1 to fail. You're going to have to open it up sooner or later anyway. ;-)

Me being me, I would get two new sensors and replace them both the same time. No point doing this little joy-fest twice!

Speaking of which, when you do get around to replacing the senders, would you be so kind and post a DIY for how you go about doing it. Some pictures and basic step-by-step of how you did it would be greatly appreciated.


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Looks like you've nailed it.
> 
> The only other thing you might try is to swap both sensors and run the test again. If 2 failed the first time, when you swap it, you should expect 1 to fail. You're going to have to open it up sooner or later anyway. ;-)
> 
> Me being me, I would get two new sensors and replace them both the same time. No point doing this little joy-fest twice!


Yeah think so. Gonna do repairs soon and will follow up here what results are.

This forum is super usefull so maybe i can add some knowledge of the things i encounter with my MK2 TTS Coupe


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## SwissJetPilot (Apr 27, 2014)

Anything you can contribute is always appreciated. 

I really hope this doesn't happen to me because as you may have noted in the WSM, Roadster owners have to drop the tank to get to get the senders out! :x


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Anything you can contribute is always appreciated.
> 
> I really hope this doesn't happen to me because as you may have noted in the WSM, Roadster owners have to drop the tank to get to get the sender out! :x


Yikes.... that would give me headache too


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## SwissJetPilot (Apr 27, 2014)

If this TT is new to you, it would be worth going through this list as many of the service items recommended here are not on the Audi recommended maintenance schedule -

*FAQ - Mk2 TT Recommended Maintenance & Service*
https://www.ttforum.co.uk/forum/viewtop ... &t=1932049


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> If this TT is new to you, it would be worth going through this list as many of the service items recommended here are not on the Audi recommended maintenance schedule -
> 
> *FAQ - Mk2 TT Recommended Maintenance & Service*
> https://www.ttforum.co.uk/forum/viewtop ... &t=1932049


Thanx  allready read it ..... very usefull (and correct) stuff..... i'm doing all repairs myself with help from friends who are all VAG addicts ... so not new to the TT but new to this forum ... it was the only place worth mentioning my fuel issue after a lot of googling

I replied on the Haldex IV filter which doenst need servicing according to Audi (lol)... trust me it DOES (good post on that) , when my came off it was dirty as hell.


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## jaydee77 (Feb 20, 2021)

Also did the taillight GROUND fix....

You know when one light is more bright then the other and the annoying light error in the DIS...

Bypass it in the taillight and ground it to your rear booth ground points... great fix and easy DIY


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## SwissJetPilot (Apr 27, 2014)

[smiley=thumbsup.gif]

I found this Youtube and wanted to post it for future reference. A few good points when removing or installing the pump and sensor. And here's a list of potential fault codes related to the fuel pump and sensor, some of which have more information on the Ross Tech website -

*Similar faults - *
P0148 - Fuel Delivery Error
P0627 - Fuel Pump A Control Circuit /Open
P025A - Fuel Pump Module Control Circuit/Open
P0191 - Sensor for fuel pressure - implausible signal
00438 - Fuel Supply Sensor 2 (G169)

*Faults Available on Ross Tech's Website - *
P3073 / 12403 - Fuel Pump Circuit Electrical Malfunction
P0230 / 16614 - Fuel Pump Primary Circuit: Malfunction
P0628 / 17069 - ECM Power Relay Control Circuit (J271): Open Circuit
16471 / P0087 / 000135 - Fuel Rail/System Pressure: Too Low

*Fuel pump EASY replacement on TFSI engine | Hitachi Automotive*


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> So what u guys think of that ? Am I right to say that fuel lever 2 sender is really dead (G165) and fuel sender 1 is OK (G) ??


It sure looks like it, but I would caution VCDS requires communication with the device to provide a reading. If you have a bad connection or damaged wiring you could be led down the wrong path.

Looking at your data, a resistance value of 0 from sender2 seems unbelievable (unless wiring shorted to ground). Maybe the signal is just so far out of range VCDS can't interpolate? Before I replaced the senders, I'd retest with your meter.

Combining your VCDS results with the resistance measurements taken at the fuel level senders will help you isolate the cause (i.e. bad resistance measured at the sender + bad VCDS reading = bad sender. Good resistance measured at the sender + bad VCDS reading = bad connection or programming).


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > So what u guys think of that ? Am I right to say that fuel lever 2 sender is really dead (G165) and fuel sender 1 is OK (G) ??
> ...


Good point. I'll retest on de 3-pin connector this week.

Gonna test pin 1+2 but also 2+3 (2+3 should be 340 Ohms)....


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## SwissJetPilot (Apr 27, 2014)

I found this Youtube where the mechanic had to replace a damaged fuel pump/sensor in a VW Golf TDI. The car was rear ended, and the force of the collision caused the two vertical posts to snap, resulting in the pump and sensor laying horizontal inside the tank. If the multimeter and VCDS readings aren't making any sense, it may be worth a look-see inside the tank to see what's going on.

*VW Golf TDI Fuel Pump/Level Sensor Replacement*


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > So what u guys think of that ? Am I right to say that fuel lever 2 sender is really dead (G165) and fuel sender 1 is OK (G) ??
> ...


Hi .... and the story continues .... I retested sensor 2
On pins 1+2 it says 200 Ohms
On Pins 2+3 it says 340 Ohms and thats the correct value if i understand Chaos....

But VCDS sees no data.... so im beginning to think this is something else.... mainly because my ambient temperature is way off. The dash says its -10/-13 degrees while its like 15 degrees plus.... being the cheapest part i replaced the sensor with a brand new original temp. sensor and guess what...

after replacement still -10/-13 degrees....

So both the tank malfunction AND the temp problem started at the same time... desperate seeking advise now


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## SwissJetPilot (Apr 27, 2014)

For the temp sensor fault - 
http://wiki.ross-tech.com/wiki/index.php/00779

Looking at the schematic, *G17* (OATS), *G* Fuel Level Sensor (#1) and *G169* Fuel Level Sensor (#2) all report to *J285* Instrument Cluster Control Module. Wonder if it's the ICCM and not the sensors...???

Have you attempted an Basic setting or Adaptation for any of the sensors?


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> For the temp sensor fault -
> http://wiki.ross-tech.com/wiki/index.php/00779
> 
> Looking at the schematic, *G17* (OATS), *G* Fuel Level Sensor (#1) and *G169* Fuel Level Sensor (#2) all report to *J285* Instrument Cluster Control Module. Wonder if it's the ICCM and not the sensors...???
> ...


Yes but the G sensor is functioning (measured correct values in VCDS).

Also a common thing is that G169 and G17 uses earth connection 410 (Earth connection 1 in main wiring harness). But i have no clue where that 410 wire is or where the ground point is.

And of course could be an instrument cluster thing but ... i rather don't want to think of that LOL [smiley=bigcry.gif]


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## jaydee77 (Feb 20, 2021)

Oh and for the temp sensor:

It doesnt give a fault code... only incorrect values.... With rainy weather it sometimes throw the fault 00779


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## SwissJetPilot (Apr 27, 2014)

Grasping for straws here, but I found this for the Mk1. No promises 

_Reviving an old thread because I found it first before I found a solution. In case anyone else ends up here looking for a solution to the issue of the fuel gauge always showing full here it is:

1. Pull the fuse for the fuel pump.
2. Turn the ignition key to on (without starting the car).
3. Turn the ignition off.
4. Put back the fuse for the fuel pump.

This will reset the computer, and you should have a fully functioning fuel gauge again._

Source: https://www.audiforums.com/forum/audi-t ... er-165875/


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Grasping for straws here, but I found this for the Mk1. No promises
> 
> _Reviving an old thread because I found it first before I found a solution. In case anyone else ends up here looking for a solution to the issue of the fuel gauge always showing full here it is:
> 
> ...


Did something similar:
Disconnected battery negative
turn on igniton
turn off
Connect battery

No luck there.. same stupid errors... i still dont know what to choose
Replace fuel sender
Replace dashboard
Replace wiring (but that is not so easy with the dash 32 connector)


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## SwissJetPilot (Apr 27, 2014)

There are several companies in the UK that specialize in Instrument Pod repairs. It might be worth an email to them, describe everything you've gone through, and see what they say.

Meanwhile, if you replace both fuel level senders, at you know you have good ones, so that's off the list. You can bench test them both before installation just to double check they're okay. Then install them in and test then test them again using the connector pins in the covers just to make sure everything's still reading correctly.

Still, it's a bit odd a brand new OATS would read incorrectly. :?


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> There are several companies in the UK that specialize in Instrument Pod repairs. It might be worth an email to them, describe everything you've gone through, and see what they say.
> 
> Meanwhile, if you replace both fuel level senders, at you know you have good ones, so that's off the list. You can bench test them both before installation just to double check they're okay. Then install them in and test then test them again using the connector pins in the covers just to make sure everything's still reading correctly.
> 
> Still, it's a bit odd a brand new OATS would read incorrectly. :?


Yeah a brand new G17 should have fixed the temp display in dashboard.

Im gonna remove Sender 2 and measure its resistance outside the tank. If those values are correct im gonna look into dash pot repairs :S

Unfortunately i live in holland so gonna search for a dutch repair


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## SwissJetPilot (Apr 27, 2014)

Ah, the land of cheese and wooden shoes! Nice 

You might want to run a Forum search for "Netherlands" and see if you can contact some of the Dutch Forum members who may be able to recommend someone in the NL to do the instrument pod repair. Look up *TT-driver* or *Yesj* or *Fritschy* as I believe they're Dutch. If you can't PM, let me know and I'll send them a PM on your behalf and point them in your direction.


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> SwissJetPilot said:
> 
> 
> > For the temp sensor fault -
> ...


I don't think you can assume G is good simply because you read a value in VCDS.
Earlier you stated that you measured 60 ohms on G pins 2 & 3. This is out of the expected range (especially if you believe your tank is ¾ full).

I would go back and confirm your measurements at G. If you still getting ~60 ohms I'd suggest taking a small nylon or rubber hammer and tapping the plastic cover (nothing too hard, don't want to break anything) then retest to see if your float was stuck. (Hell give G169 a whack for good measure... I've found machines sometimes need to know who's in charge) :wink:

As SJP pointed out, your ICCM is the common denominator and quite possibly the cause of your issues, but testing the fuel level senders is done in isolation (disconnected from everything) so your ICCM isn't in play at this point. You need to verify both senders are working before adding more variables to the equation.

According to the testing procedure, I would expect both senders to agree with each other (meaning if they don't, one has to be bad) but it's possible there is more going on since the fuel tank has a split design and fuel levels might not be equal on both sides.

If you can't get resistance reading withing spec, I'd pull both senders and check them through their range before I bought another part.


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## SwissJetPilot (Apr 27, 2014)

FNChaos said:


> If you can't get resistance reading withing spec, I'd pull both senders and check them through their range before I bought another part.


@ *Jaydee77* - Exactly as *FNChaos* stated - pull both sensors out of the tank and bench test them.

*@ FNChaos* - How is the ICCM is taking two different signals and reporting them as a single value on the fuel gauge?


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > SwissJetPilot said:
> ...


Yes I agree ! Witch VCDS sensor G measured 80 Ohms so maybe i didn't test accurate the first time so gonna do again. I think the tank is now half full maybe less so i should get more then 80 ohms now.

Yesterday measured G169 and that one still 200Ohms on 1+2 same as first test but that seems incorrect. I allready looked at G169 in the tank and the float wasnt stuck there.... it was indeed "floating" on the petrol.

Gonna pull those sensors and test them outside the tank. To be sure


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## jaydee77 (Feb 20, 2021)

Some more info ....

I told before it all started in the cold with a total reset (just like when u disconnect the negative from the battery and reconnect) and dash display in german.

We tested the old battery and there was a shortage in it. So root cause seems a battery shortage. Replaced the battery allready so thats a good step.


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## SwissJetPilot (Apr 27, 2014)

Just as an FYI, I contacted Ross Tech about this issue since they don't list the *Fault 00438 Fuel Supply - Sensor 2 (G169)* on their website. Andy Smith replied and asked for the AutoScan report but as it wasn't posted, I gave him the link to this post. If you want to contact Ross Tech directly, you can use the email address below and be sure to include your entire AutoScan report as a TXT file with the email.

*[email protected]*


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> Just as an FYI, I contacted Ross Tech about this issue since they don't list the *Fault 00438 Fuel Supply - Sensor 2 (G169)* on their website. Andy Smith replied and asked for the AutoScan report but as it wasn't posted, I gave him the link to this post. If you want to contact Ross Tech directly, you can use the email address below and be sure to include your entire AutoScan report as a TXT file with the email.
> 
> *[email protected]*


Thanx for your support Swiss (and Chaos).... tomorrow im gonna do one last all-in test procedure. Focussing on G17 temp sensor because that seems straightforward ... new sensor should give correct values

- Gonna test sensor on Ohms vs Temp
- Gonna test voltage supply on wire with ignition on
- Gonna test resistance in wire from dash connector pin to pin on temp connector

Now if the voltage is too low but the resistance in the wire is OK (< 1.8 ohms) then i think the following is true:

Our big hunch is the instrument cluster because the voltage on both sensor wires seems too low. G17 should have 5volts and the last time we checked it was 0.45. Could be the voltage regulator in the cluster that fails. Doesn't happen often on the MK2 but hey sure sounds like it.

In the end i will find the problem and will write a global report for this community.


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## jaydee77 (Feb 20, 2021)

So here are the results of today testing.

Wiring is good
Temp. sensor itself measures 1500 Ohms so according to audi that should be around 15 degrees which is also good

Now with a measuring pins we tested the dash connector power supply (pin 1/2 & 18)

All measured 12 Volts so thats ok too

With the dash connector on the instrument & ignition on we tested pin 24 & 6....

Both measured 0,25 volts and not 5volts.... so u guys agrees that the instruments doesnt provide the power the sensors need. So the sensors arent defect.


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## SwissJetPilot (Apr 27, 2014)

There's a VCDS dash pod test for the Mk1 that may help as it explains how to test it.

*Testing the dashpod gauges*
https://www.ttforum.co.uk/forum/viewtop ... =2&t=94411

*VCDS dashpod testing*
https://www.ttforum.co.uk/forum/viewtop ... &t=1518385

*TTweaker's Guide*
https://auditttuning.org/audi-tt-to-fol ... ers-guide/

Here's a Youtube video on how the VCDS can be used for the Output test -

*VW Golf 5 instrument cluster output test*


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## jaydee77 (Feb 20, 2021)

SwissJetPilot said:


> There's a VCDS dash pod test for the Mk1 that may help as it explains how to test it.
> 
> *Testing the dashpod gauges*
> https://www.ttforum.co.uk/forum/viewtop ... =2&t=94411
> ...


Hi Swiss. Allready did the output test of the dash to see if gauges are working and they are working fine. Problem is that the sensors get their power from the dashpot and thats too low.

Im quite convident it must be a simple voltage regulator in the dash thats broken. Otherwise their would be 5volts to the sensors (not 12v... the voltage regulator in the dash must provide a stable 5volt to sensitive sensors).

So when the sensors don't get 5volts they just dont work... or in case of temp.sensor give back wrong data

Gonna make an appointment (found a repair shop) to test the dash en fix the regulator.


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> With the dash connector on the instrument & ignition on we tested pin 24 & 6....
> 
> Both measured 0,25 volts and not 5volts.... so u guys agrees that the instruments doesnt provide the power the sensors need. So the sensors arent defect.


Did you measure between pins 24 & 6, or did you measure pin 24 to ground and pin 6 to ground ?
What is your resistance between pin 28 and chassis ground?


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > With the dash connector on the instrument & ignition on we tested pin 24 & 6....
> ...


I took the dash connector out of its blue casing. Then on the side where the cables go in i put a measuring rod in pin 24 (so together with the wire). Put connector back and turned ignition on. Then measure output on rod (to good groundpoint of car)

Pin 24 to ground

Pin 6 to ground

Just to check what voltage the dashpot puts on those pins... both too low voltage and not 5volt.

With the same rod i tested the terminal 30 pins and they gave 12 volts (good)


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> FNChaos said:
> 
> 
> > jaydee77 said:
> ...


Were the voltages still 0.25 or something different like 2 or 3 volts ? 
Sender is a voltage divider so the total (P24 to gnd + P6 to gnd = 5v)


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## jaydee77 (Feb 20, 2021)

> Were the voltages still 0.25 or something different like 2 or 3 volts ?
> Sender is a voltage divider so the total (P24 to gnd + P4 to gnd = 5v)


Sorry don't quite get this.

Pin 24 is the ambient sensor. From G17 test manual it stated the G17 needs 5volts. SO i thought lets check that on the dashconnector (while plugged in) and that measured 0,25 volt.... same for pin 6 (which is the fuel sender 2 signal wire).

am i missing something ?

The ambient sensor is the other thing that doesn't work even after replacement with a brand new one. SInce that one is only 1 sensor it was easier to start with that problem. And i expected 5volt on pin24 from the dashpot but only gave 0,25 volts.

After that i also checked pin 6 (fuel sender 2)


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## FNChaos (Nov 30, 2016)

jaydee77 said:


> > Were the voltages still 0.25 or something different like 2 or 3 volts ?
> > Sender is a voltage divider so the total (P24 to gnd + P4 to gnd = 5v)
> 
> 
> ...


Just trying to determine if you had a good return path to complete the circuit since you stated _"both too low voltage and not 5volt"_ without any measured value.

If you still measured 0.25v I would agree you've lost your 5v supply. If you measured something different then there still 'might' be a wiring issue.


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## jaydee77 (Feb 20, 2021)

FNChaos said:


> jaydee77 said:
> 
> 
> > > Were the voltages still 0.25 or something different like 2 or 3 volts ?
> ...


Ah sorry. I'm dutch so maybe my english isn't quite that good 

Yeah thinking the same ... lost 5v from dashpot.

To be clear :

Pin24 to ground measures 0,25 volts (thats for the G17)

Pin6 to ground measures 0,25 volts (thats for the G169)


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## jaydee77 (Feb 20, 2021)

Ok guys... good news !!

Yesterday my dash came back to life.... just like that ! Temp. Sensor working again and fuel gauge also working

LOL ... Its a kind of magic i think ??? The only thing i can think of is the following:

Saturday we disconnected the dash for a longer time (to test the connector & stuff) like more then 30 minutes.... so it seems like some kind of reset :S In the end it is just like the post Swiss mentioned:

https://www.ttforum.co.uk/forum/viewtop ... &t=1929627

I'm totally baffled but glad i didn't just replace parts and investigated with patience. So for others who have a fuel gauge stuck on empty:
- Check if temp (ambient) sensor G17 is acting weird too
- Try disconnect dash (instrument cluster) for more then 30 minutes
- Try disconnect battery negative and leave it disconnected for more then 30 minutes

Then look the next day or so if things work again... if that aint the case you can do all the testing as mentioned in this post because all that info is correct too

Electronics are a bitch 

PS: Special thanks to Swiss & FNChaos for their help and good information on how to research


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