2004 b6 s4 fuel pump issue?

[AllroadMass]

For the last few days I've notice that my fuel gauge doesn't seem to be showing correct fuel level.

First time was last week. drove to dinner, tank was a little more than half full, and on the way back it was completely empty. Today tank showed almost full and I went to top it off before driving into the city, it took 7.5 gallons!

Any insights?


Sent from my iPad using Tapatalk

[gautam]

Fuel level sensor. Doubt it's a fuel pump issue.

[AllroadMass]

Fuel level sensor. Doubt it's a fuel pump issue.

That doesn't sound too expensive but I'm sure I'm wrong

Sent from my Nexus 5 using Tapatalk

[snowboardgod]

That doesn't sound too expensive but I'm sure I'm wrong

Sent from my Nexus 5 using Tapatalk

Definitely not the pump. Probably the sending unit which is a seperate piece under the seat on the driver side that I believe contains the level sensor, Jhm sells them.

[AllroadMass]

Definitely not the pump. Probably the sending unit which is a seperate piece under the seat on the driver side that I believe contains the level sensor, Jhm sells them.

They're separate? I read that the pump is on the passenger side...thanks for the jnfo

Sent from my Nexus 5 using Tapatalk

[924Carrera]

There are two sending units, one on the driver's side and one on the passenger side. The passenger side also has the fuel pump.

https://www.ecstuning.com/Audi-B6_S4.../Sending_Unit/

[AllroadMass]

Oh great! Should I do both at the same time or should I do them one at a time?


Sent from my iPad using Tapatalk

[924Carrera]

Oh great! Should I do both at the same time or should I do them one at a time?


Sent from my iPad using Tapatalk

You can use VCDS to check the output from the 2 sensors. The higher the resistance value, the lower the fuel level being indicated. If one of the sensors is bad, it should have a significantly different value from the other one. I believe 250 ohms corresponds to an empty tank.

[AllroadMass]

You can use VCDS to check the output from the 2 sensors. The higher the resistance value, the lower the fuel level being indicated. If one of the sensors is bad, it should have a significantly different value from the other one. I believe 250 ohms corresponds to an empty tank.

Coming through again! Will do it tonight when I get in and report back. Thanks bud!

Oh great! Should I do both at the same time or should I do them one at a time?


Sent from my iPad using Tapatalk

Sent from my Nexus 5 using Tapatalk

[AllroadMass]

I'm currently almost half a tank, I got 137 ohms for the sensor #1 and sensor #2 was N/A so I think we found the problem!


Now I just need to know which sensor is which so I can order the correct one from ECS...

[924Carrera]

I'm currently almost half a tank, I got 137 ohms for the sensor #1 and sensor #2 was N/A so I think we found the problem!


Now I just need to know which sensor is which so I can order the correct one from ECS...

I do not actually know which one is which. However, an easy test would be to pop the driver's side access cover off (which you'll have to do to replace the sensor anyway) and unplug it. Then run the test again, if they both go N/A then you know that's not the bad one. I say driver's side because the passenger side one with the pump is more annoying to get to, from what I've seen, but either way will work.