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Fuel Gauge always reading near zero

Sterob

Member
2006 A6 C6 3.2L Quattro Sedan
175000km

I replaced the fuel pump at 150000km. No problems with that since.

A couple of days ago, I was near empty, so I filled up my tank. ( very full) When I restarted my car, the fuel gauge remained at the 'almost empty' level and the estimated range remained unchanged.

I did a scan today with VCDS and could not find any fault codes.

I did find the section called Advanced Measuring Values and found these parameters.
I was surprised to see data for 2 sender units. After Googling I see that appears to be the norm?

Before I start to rip my car apart, does this info ring any bells with anyone?
Does a split in the sensor readings, like this, cause the fuel gauge to read incorrectly?
Does either sensor look suspicious?


I went through all the Data Blocks twice to try and find anything related to the fuel gauge, but did not see much.
The closest with Instrument Cluster, but there were no DTC's there.

Hope someone can enlighten me.
Steve
 

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good luck mate, i have the same problem with my Mercedes C63 and BMW M4 so it sounds like it's not isolated to Audi cars...
 
did you replace the in engine fuel pump, or in tank one?

not sure of your car, but my 3 8P has two sensors, one in left and other in right side of tank.

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good luck mate, i have the same problem with my Mercedes C63 and BMW M4 so it sounds like it's not isolated to Audi cars...
Thanks. I'm collecting info and tools at the moment. WIll chase up parts if/when I find the problem.
 
did you replace the in engine fuel pump, or in tank one?

not sure of your car, but my 3 8P has two sensors, one in left and other in right side of tank.

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I *did* replace the fuel tank Fuel Pump a few years ago and swapped the sender over to the new pump, and have not had any problems until now.

Yes, I think I have 2 sensors, a fuel pump on one side, and possibly a 'balancing' ( for want of the right terminology ) pump.

I have the impression that if either sender fails the gauge will read zero.... I'll do some resistance checks soon, hopefully...
 
I did a resistance check of the senders today.
Tank was originally full and I syphoned about 35L out. Tank is supposed to be 80L.
One sensor was 280 Ω and the other was 390 Ω.
I looked for a fuse relating to the fuel gauge but only found one for the instrument cluster. ( it was good ) I checked the 2 front fuseboxes and one in the boot.

Without knowing exactly how each fuel sensor is meant to influence the fuel gauge, it seems that those 2 readings are legitament.
I cleaned the connector and pins on the fuel pump cover and no change.

Can I simulate a fuel tank reading via VCDS? Other than that, cannot think of a way forward from here. Anyone got any ideas?
Steve
 
check out this thread with some useful imfo that might help you.



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check out this thread with some useful imfo that might help you.



Sent from my SM-G985F using Tapatalk
Thanks jnrdavo.
I have seen that thread in my hunt for the answer.

I have some developments.....

After checking the sensor resistances, I replaced the electrical connector and checked the fuel gaug. no worky.....

I went back on the 'Net and saw this video:
I thought, I hadn't inspected the pins of the connector yet, so I went out to do that.
I only found 2 of the pins recessed *slightly* more than the 3rd one. Not really enough for them to be suspicious to me, but nevertheless, I attempted to push them both a bit deeper into the connector. They both did seem to move a smidge....hard to tell.

I replaced the connector once again and its still not working. I went to remove the connector again and noticed that it wasn't locked on!
I had been pushing very hard when ever I replaced the connector and yet it was still not locked on properly.
I aquired a 'pushing stick' so I could exert greater force when seating the connector and heard the little 'click' I should have been listening for all along....
I tried the fuel gauge and it now works! woo hoo. Tank reads just over half full, so that aligns with the 35L I syphoned out.

Post Mortum:
I don't know if the connector was seated properly from when I changed the fuel pump a couple of years ago, and I had repeatedly failed to re-seat it properly?,or
the 2 sensor pins were retracted a smidge and that was enough for one of the sensors to go open circuit?
( I'm not convinced about the pins as they were only about 1mm set back from the 3rd one. )

Anyway, its working for now. I'll leave the back seat out for a few days to make sure its reliable.

Spare locking ring, removal tool and fuel line reconnector pliers still on the way, for nothing.....lol

I hope someone else finds this useful.

Steve
 
good to here Steve.. I've only had this happen to me in my first car (VC 4cyl commodore).. was a pain, and I remember running out of fuel a few times and having to buy and carry a spare fuel container 'just in case'!

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