[david_connoll]

I have a bank 2 post cat oxygen/lambda sensor that is reading nothing, the specialist said it was running rich and lean, would I thought would be explained by the one sensor gone and one working.
But then another guy said the Nox sensor is gone too.
Would it be likely that both would fail together?
I am going to throw in the lambda sensor and see what readings I get then.
What should I check on my obd reader to see that the lambda sensor is the issue and the Nox sensor is ok?
The engine light comes on, guessing if its only the lambda sensor it'll go off and stay off, but if its the Nox sensor also that is the issue, the ending light will still come on?

[S.H]

I would also check for leaking injectors, maybe the hole problem is there. And Bimmerprofs says that leaking injectors / running rich lead to shorter life on the sensors. So yeah... $$$

[david_connoll]

I know the lambda sensor is 100% not working, its reading nothing, but yep good point, what maybe mad the sensor go.
How can you even tell if you've leaking injectors?
The fact its all high pressure the fuel system, probably why there more issues as these cars age?

[S.H]

Yup, the nox system is a pain in the butt on these engines.. Like for the n54, the way to check for leaking injectors is to let the car stay overnight and check if the spark plugs are dry or wet the next day. If they are leaking, they will drip on the spark plugs. Lots of info on bimmeprof's website.