[Rampant513]

Hello guys,

Today after filling up the tank, I got back into the car and the gauge was only at half. I made sure that I didn’t accidentally underfill, and then checked the hidden menu 6.00.

It read: (picture of the reading)
TANK L R S
**.* 31.7 31

To me this indicates that it’s not receiving any reading from the left side fuel sensor. Do you guys think it’s broken, or just dirty? Could it be a fuse/electrical issue?

[Rampant513]

Small update: I went back to check it again, and I got this reading on the 6.00 menu:

TANK L R S
24.6 32.6 57

The gauge also went to 95% after a quick restart.

I’m going to run some chevron techron through on my next fill up and see if it goes away for good.

[gbalthrop]

Originally Posted by Rampant513

Small update: I went back to check it again, and I got this reading on the 6.00 menu:
TANK L R S
24.6 32.6 57
The gauge also went to 95% after a quick restart...

While you MIGHT have an issue with the LEFT Level Sensor itself, I would think it's as/MORE Likely an issue with
the wiring, either at the Left Tank connector X691 in attached ISTA SSP, or at JBE Connector X14271.
Note the two Level Sensors are "hard-wired" to the JBE, and the JBE then sends signals to KOMBI via K-CAN.
So if you have INPA or ISTA, you can connect to JBE and read Live Data of two Level Sensor Signals.
The attached diagrams show Location of Connectors & you can check each for corrosion & clean. I would NOT open
the Tank UNLESS examination & cleaning of external connectors fails to rectify the issue.
SSP wiring diagram with Location & Connector View for relevant components are attached.

Thanks for the tip on "Hidden Menu 6.00", as I had forgotten that can be used instead of INPA/ISTA to read
individual Level Sensor signals.
George

[Rampant513]

Originally Posted by gbalthrop

While you MIGHT have an issue with the LEFT Level Sensor itself, I would think it's as/MORE Likely an issue with
the wiring, either at the Left Tank connector X691 in attached ISTA SSP, or at JBE Connector X14271.
Note the two Level Sensors are "hard-wired" to the JBE, and the JBE then sends signals to KOMBI via K-CAN.
So if you have INPA or ISTA, you can connect to JBE and read Live Data of two Level Sensor Signals.
The attached diagrams show Location of Connectors & you can check each for corrosion & clean. I would NOT open
the Tank UNLESS examination & cleaning of external connectors fails to rectify the issue.
SSP wiring diagram with Location & Connector View for relevant components are attached.

Thanks for the tip on "Hidden Menu 6.00", as I had forgotten that can be used instead of INPA/ISTA to read
individual Level Sensor signals.
George

Wow, thank you for the wiring diagrams. I will check the connectors this weekend and see how they’re doing.

[gbalthrop]

Forgot you were new to Forum. Welcome!
Attached is pdf: "E9x References 210523 Revision" which has links to MANY helpful References for your car, such as Bentley Manual, INPA & ISTA downloads, BMW sites for new owner registration, Recalls outstanding, pdf Manuals, etc.

You can get ALL the good stuff on your own computer, and maintain/understand your vehicle yourself with so much FREE help available. One suggestion: Owners of 2007 model vehicles should ALWAYS indicate build Month/Year, as significant Electrical Changes (JB Layout, & E-box contents) occurred effective 3/1/2007 in middle of 2007 Model Run.
George

[Artmasterx]

I had a similar issue, and I think this solved my problem. Maybe it can help other as well.

After replacing my fuel pressure regulator, I had an issue where the left side level sensor would not read full. Typically the fuel gauge would read about 7/8 after filling up, and the resistance of the left sensor would be significantly below its max value of ~990 ohms.

I just took out the FPR again to try something. Not unhooking it completely, I left the tubes connected.

I tested the resistance of the float sensor from bottom to top, and it goes from ~50 to ~990 ohm, which I think is the right range. It also reads this same range in the hidden menu (so nothing weird with the wiring in between). How to get to the hidden menu, if you don't know: https://www.e90post.com/forums/showthread.php?t=4320. Menu 06.02 (I think) shows the resistance value of the fuel level sensors.

My working theory was this...
The FPR has that spring arm that basically goes straight down into the tank (not talking about the level sensor arm, but the plastic extender thing with the spring). And the level sensor is mounted to it. When I had the FPR out, there was a decent amount of play in that spring arm when fully extended. I think I bought the VDO version of the part. If it is "bent" in the fully extended state, then I think it could effectively make the level sensor not be able to float to the top of its range (because the sensor housing is now at an angle). I think this is especially true if the arm is bent toward the left side of the car, which is think is more likely with the way you have to insert the FPR.
If this is true, then the sensor may not read the full resistance and therefore the car won't think the left side tank is full, even though it is.

Now, if you look down in the tank below the FPR, you will a shallow depression in the bottom of the tank (straight down the opening, slightly forward on the bottom of the tank). This depression is meant to hold the tip of spring arm in the same place during bumps, etc. And I am sure it is also to make sure the level sensor is positioned correctly as well, since the sensor is attached to spring arm.

This depression also has a small (smooth) raised lip around it. My theory is that the when I put the FPR back in originally... and also the second time after I took it out again to check it... that I wasn't careful to make sure the spring arm tip was in the depression. It may have been caught on the lip of the depression, and then would be tilted at an angle when I close up the lid which could make the sensor read incorrectly. And because if the lip, it will not work it way back into the right place.

I tested it out today and it now seems to be working correctly. So I hope this may help some others as well.