1st Gen. 1 Series (2004-2013 | E81, E82, E87, E88)
I had my E87 116i (N43B16AA) in for an oil change and a full check. They read the error codes, and it came up with the 30E9 code. I knew it was there, as it had been the case for some time now. But they recommended an NOx sensor replacement, which is serious money. I dug into it a bit more, and...