Just changed spark plugs and upstream O2 sensors. Observations and a question.

[bmw540san]

I just got this car and while the service history is pretty good, these were original (93k miles) and I don't really believe much in 100K miles BMW recommended replacement. Sure, car was running fine and there are probably cars here with originals over 100k miles but the new components can definitely help.

I got great deal on both. $52 for plugs and $98 for sensors. This is $150 well spent.




The plugs look to be in decent shape but obviously tired and this one is in the worst shape, probably due to VC gasket leak that was fixed just before I bought the car. It's the one closest to firewall on passenger side and in my experience when the VC gasket fail, oil likes to pool in that spot and slowly works its way around it. The rest of the plugs look much better than this one.





It's hard to tell the condition of O2 sensors as the lambda is hidden behind the shield but one of the sensors wasn't actualy original which is the proof they don't last forever.




While changing passengers side o2 sensor, I discovered that wiring loom around the transmission electrical feed has completely disintegrated due to heat and I've rewraped it with 500F silicone tape.




Now the question: Anybody knows where this line connects. I'm certain I didn't accidentally disconnect it as the car is running fine (actually slightly better). I can compare it to my 540 but it's non vanos and I figure somebody here should know. I'm suspecting that it may not go anywhere but I'd like to know for sure. Thanks.