Originally Posted by cncmastr

Hi guys,

My 4.8is X5 (E53) has 112K miles, I think the O2 sensors are original. My gas mileage is okay, I suppose. I was thinking of replacing the pre-cat O2 sensors prematurely, but I saw on the DIY for the 3.0 model (m54) you need to re-route the cables back to the engine. Is it different on the N62 4.8is? Do I need to route back to the engine? It looks like from under the truck it connects to a box mounted right on the transmission. If that is the case, it looks pretty easy (which is relative I suppose).

Thoughts?