Fixed my 4BCC CEL

[Markstre302]

Hey guys, new owner/member here. Picked up a 2011 X5D and it had a CEL pop up for 4BCC on the drive home. It was a deal and we knew it was going to have issues. Dig into the forums here (and bimmerpost) to research best practices for repair/upgrades to issues.

Found the price of the passive def tank ridiculous so I went and built myself a, let’s just say highly functional, 4 wire patch harness out of a trailer wire extension because the connector is basically water tight and the wire colors basically match the existing level sensor harness. 10k ohm resistor soldered in between each wire and the signal wire. With a second harness cut in two and wired in I can replace or update the harness if needed.

So I crawled under the car, pulled the passive tank out and went wait. Where is the 4 wire harness? Time out, back to forum, realize I built a harness for the active tank. Doh! Go back out, measure resistance on each level sensor and find the top sensor has an open circuit.

Started looking at where the best place to wire a resistor would be, and I looked at the end of the harness.

Well, I think a resistor will fit in that corner and I can just stick some leads into the connectors.

Well what do you know, it works. Plugged everything back in and cleared the code. Two days later and still clear. Going to fill the tank and get our smog test done.

Happy to help with any questions and will do a proper intro post once I’m on a computer and not my phone. Sorry the photos wouldn't load directly from google photos, so I had to shrink them and attach manually.