[Sharj10]

Hey so I had a fault code for bank 2 sensor 1 o2 sensor and I was in the middle of a diy. I came across this thing that was getting in my way that wouldn’t let me get to the plate holding the sensor. Would any1 be able to tell me what it is, or a diy video for N51 o2 sensor replacement? I didn’t see this on other diy o2 sensor change videos

[PhaseP]

N51 has secondary air something for better emissions. It looks like secondary air valve, number 8 in this diagram:

https://www.realoem.com/bmw/enUS/sho...diagId=11_4000

In theory you could unbolt it and set it aside, but there is very good chance of breaking the studs those nuts are on due to age and corrosion. Being on the exhaust side, that section get hots and when cooled down it will get even tighter with corrosion developed on the threads. Don't blame me if the studs brake if you take the route of removing those nuts. I don't own an N51, so don't have any first hand experience.

I suggest Google more for N51 02 sensor replacement.

(You would need a new gasket too if you take that route. )

[TriumphTim]

I think I unbolted this successfully a year or two ago when I did my valve cover on my N51 at 100k miles.

Hit it with PB blaster, start the engine to get the nuts and studs hot, should come off pretty easy although you never know...

The plastic hose may break too, though I have taken the other end off a few times with no problems.

[Sharj10]

Would it make sense to replace that part completely? Figured if I buy the part it would come with a new gasket and bolts as well

[TriumphTim]

Honestly, I wouldn't, that part 11727557909 is $100, some suppliers include the gasket. The nuts are probably available at an auto parts or hardware store.

If you soak with PB Blaster and use a gentle touch with the hardware, it should come off fine.

To remove the hose, you press the ringed tabs together and slowly work off, the hose itself it much more like to crack or break.