I would love to see a good DIY video/pics for doing this replacement on an E70. I've found others for different model BMW's and they seem so much easier.

I'm also getting code:
- Fault: Heater for lambda probe front catalyst 2
- Code: 002C9D

Which, if I am reading correctly, indicates a probable fault with my O2 sensor as well. And since it refers to "catalyst 2", is that to mean it's #2 in this diagram?

RealOEM.com - Online BMW Parts Catalog

I'm reading it as front (pre-cat) sensor of bank 2 which is the driver's side. I think your parts diagram is for an inline 6 cylinder engine.

Now I'm really confused. The diagram is from realoem and I gave the last 7 digits of my VIN to get to it.

When I look down at the engine, on the passenger side I see the front one (part #1 in the diagram) which looks to be relatively easily accessible, and the rear one (part #2 in the diagram) back under the microfilter housing towards the firewall.

The code would seem to indicate that it's the rear, harder to access, probe that needs to be replaced. But it looks like a number of things have to come off to get to it.

When you get an O2 sensor **HEATER** code, that usually means an open circuit to the O2 sensor. There are 4 wires to the sensor- two get the actual signal, the other two are for a heater to warm up the sensor.

If you reset the code and, on next start IMMEDIATELY get that code return, it is the heater in the sensor OR the connections to the sensor OR the fuse to the heater circuit.

And PHL08- have you looked from underneath? Ive not done it on E70s, so no idea. But I dont think Ive ever done an O2 from above on any car....

Oh, hate to change it to find out it was a fuse or connector loose.

I cleared the code and took the car around the neighborhood. No engine light. But when I stopped and checked the codes, it was back. When I started the car again, the engine light was on.

So, if it's the heater in the probe then the probe needs replaced. I can check the fuse, if I knew where/which to look for. Any thoughts?

The connectors will require so much removal of other parts that I might as well swap the probe at that point. Bosch probes are going for about $130 now.

I'm still scratching my head from 2 posts ago when it was suggested my bank 2 is on driver side, though the N52 engine in this scenario is a straight 6 which, I thought, puts the 2nd bank in the rear for cylinders 4-5-6.

Sorry to confuse you. My original post was about the V8 engine in my X5. Just assumed you were talking about a V8 also. In your inline 6 engine, the bank 2 pre-cat sensor is the one closest to the firewall on the exhaust manifolds (#2 in the RealOEM diagram). Should be easily accessed from above. Might need to remove the parts that hold the weather stripping and A/C filters near the windshield for easier access. Don't worry about the heater probe fault. Just replace that sensor.

Bothers me that you have a o2 or catalyst issue at 70k o2 sensors should go 100k. I fear.for.your catalytic converters. Something is wrong here and you must have it diagnosed. Any good shop that does emissions testing should be able.to figure.it out.