Dodgy fuel gauge

eisenberg1

Hi,

Audi A6 '09 with a fuel gauge giving sporadic readings. It current,y has a full tank bit will show as empty, half full, all different reading at different times.

Easy fix? Expensive?

Thanks

jimgoose

It's probably the fuel-level sender float valve, which IIRC can be found on those behind an inspection plate under the back seat. It should be plugged into VCDS first though, if possible, to see what him Computer say. I also have a notion there are two sender valves in those, on a "saddlebag" tank, and some sort of auto-balancing between them by electric pump. A quick dekko on Ye Bay of Gee suggests the sender units themselves are quite pricey.

eisenberg1

jimgoose wrote: »

It's probably the fuel-level sender float valve, which IIRC can be found on those behind an inspection plate under the back seat. It should be plugged into VCDS first though, if possible, to see what him Computer say. I also have a notion there are two sender valves in those, on a "saddlebag" tank, and some sort of auto-balancing between them by electric pump. A quick dekko on Ye Bay of Gee suggests the sender units themselves are quite pricey.

Thanks Mr Goose, while a lot of the above is gone over my head, I get the gist. Perfectly ok to continue driving I assume, as long as one remembers to put diesel in;) Ballpark for replacement and fitting?

jimgoose

eisenberg1 wrote: »

Thanks Mr Goose, while a lot of the above is gone over my head, I get the gist. Perfectly ok to continue driving I assume, as long as one remembers to put diesel in;) Ballpark for replacement and fitting?

Oh fine, yes. But bear this in mind - there is a small but non-zero chance that the balancing pump between the two "saddles" is gone arseways, so you *might* have only half as much diesel as you think you have. How much, I have no clue - it could be in the region of €400-€500 at a capable garage.

eisenberg1

jimgoose wrote: »

Oh fine, yes. But bear this in mind - there is a small but non-zero chance that the balancing pump between the two "saddles" is gone arseways, so you *might* have only half as much diesel as you think you have. How much, I have no clue - it could be in the region of €400-€500 at a capable garage.

Jeez! Ok cheers.

biko

Yeah, if gauge moves around arbitrarily it's probably the sender as suggested.
You can still drive but can't really trust it. Keep car topped up and you should be ok until you have replaced it.

Do you intend to replace it yourself? You posted in DIY forum.

eisenberg1

biko wrote: »

Yeah, if gauge moves around arbitrarily it's probably the sender as suggested.
You can still drive but can't really trust it. Keep car topped up and you should be ok until you have replaced it.

Do you intend to replace it yourself? You posted in DIY forum.

Whoops, no I won't be doing that, it will be going toga rage.

My apologies.

biko

No worries, moving this to main forum.

Check with a few local indy mechanics and someone may even have an old unit to swap with.

jimgoose

eisenberg1 wrote: »

...it will be going toga rage...

Mmm. Much like what Aristotle got when he took his Audi to a main dealer. :pac:

eisenberg1

jimgoose wrote: »

Mmm. Much like what Aristotle got when he took his Audi to a main dealer. :pac:

:)surely Archimedes under the circumstances.....eureka and all that:D

jimgoose

eisenberg1 wrote: »

:)surely Archimedes under the circumstances.....eureka and all that:D

Well, he did get screwed. Arf!

barneygumble99

Did battery die recently by any chance?

eisenberg1

barneygumble99 wrote: »

Did battery die recently by any chance?

It didn't die, or need to be jump started, but did give an indication of "low charge " a week ago........

biko

Interesting, seems this can be an issue for Audis.
Bad/empty battery can cause fuel gauge to show empty. It usually resets itself after a while when a good battery is put in.

Get battery tested.

eisenberg1

biko wrote: »

Interesting, seems this can be an issue for Audis.
Bad/empty battery can cause fuel gauge to show empty. It usually resets itself after a while when a good battery is put in.

Get battery tested.

Ok, it's actually my sons car ( no Da, I'm not buying a corolla:D) so I will pass the info on and most likely give it a bit of time and see if it sorts itself. Will keep you all posted.
Thanks

eisenberg1

Car was under warranty and went back to dealership. Per dealer it was the sensor, it's now repaired and appears fine.

Thanks of for the input.