Hello, if you don’t mind, can you explain a bit in detail what you did? I am getting the 4bcc error code too. There are two sensors I’m thinking on the passive tank. One for high level and one for low level def.. As a I have DEF in the tank what should the resistance reading be on the wiring? Is it a 10k ohms resistance when the tank is empty or full or doesn’t matter on fill level?

On the 335d i was able to buy the active/passive tank “basket type” sensors from VW rather than purchasing the entire DEF tank from bmw. That was a direct diy install.

Thanks