[robnitro]

I had the bank 2 code on my x5 a while ago and in research it's the 456 injectors that share a common wire. One of my injectors had an intermittent bad ground which became worse within a short time. A restart fixed my issue but it became more often and took longer to get restarted.
If the fault is a bad ground, it will pull down the voltage of all injectors on that bank, making the dde not sure which inj is specifically bad.

On the x5 the plastic partitions can crack and leak water onto the engine cover and soak the foam, corroding injector 5 and/or 6. Not sure about the 3 series, but check to see if your foam is wet.
Also with a multimeter take an ohm reading from ground to each of the pins of injectors 4 5 6.
Neg lead clip to a ground point in the engine bay. Pos lead use for testing.
First check you have a good ground by touching the red lead to the engine block/body, expect around 0 ohms. Then check an injector both pins with red lead one by one and after recheck that your ground is good by touching the red to metal on the block/body.

You will see which injector is bad, for example using my readings from memory:
Inj 4 each pin around 300k ohm to ground, like 123
Inj 5 each pin around 500 ohm to ground!
Inj 6 each pin around 4k to ground!?

In this case 5 was the culprit and 6 was next to fail. I changed both and no issues since.

The denox codes could be another issue or caused by the injector issue, not sure.