[M.chowdhury1]

Ok so I've went to my garage in my 320i 2007 e92 and they told me I need a new lamba oxygen sensor. I then did my recalls in bmw and they told me I need a nox sensor.

I bought a nox sensor from bmw for £450 and it has not resolved the issue of my rough idles, loss of power etc.

I then took it back to my garage who said I need a new oxygen sensor after cat. (Down below is the code and imagine).

Any advise would be nice and where can I purchase a good oxygen after cat sensor? I don't want to pay the dealership a stupid amount of money

[sorin1987]

They did the same with me. The error shown by the O2 sensor is just the symptom not the cause so you can replace all your sensors and still have the misfire. Let me guess, it's something like fuel mixture too lean/rich? What are the exact symptoms? Can be spark plugs/coils, injectors, cracked valve cover, Vanos solenoids.
How many miles does the car have? I see you are in London. All the dealers I've tried (Berry Heathrow and Ciswick) are a bunch of losers who have no idea how to fix their own cars. They actually proposed to change everything that throws an error until nothing else seems wrong. No investigation whatsoever.
Give us more details and we can maybe narrow the problem down.

EDIT: I could not see any attachments if your message had one

[M.chowdhury1]

Well thank you for your reply and yes I'm based in east London.

I just had the full service completed however bmw have told me possibly injectors need to be replaced (maybe). My 2007 320i e92 has 95k miles and I assume from the garage OBD reader than their is a misfire number 4.

I have got the valve cover done today and the same problem occurred. My garage recommend me to get the oxygen sensor after cat completed so Ive agreed and waiting for the part to come in tmo so I can get it done.

From my previous post, I'll upload the image of the codes again

[sorin1987]

My injectors started acting up around 72k miles. I changed 3 of them which were leaking. I was experiencing rough idles at start up and a check engine warning from time to time.
The injectors are a known issue with the E90, though since you have the 2000cc engine one you might not be affected.
Anyway, injectors would have been my first guess. They are expensive though so you might look at a bill around £1000 (for 4 injectors) at the least.
Let us know what the issue was when you find out.

[M.chowdhury1]

I have the 1995cc or something engine, on my bmw health check they did say '(ingectors May need changing) but I really don't want to spend almost a bag on just injectors

Tomorrow I'm getting the oxygen sensor after cat done so I hope the issue fixes then. I may also need some wheel speed sensors due to the traction light fluttering on randomly