Finally Fixed
To complete the story, I finally got around to dealing with the spinning 16 mm hex bolt in the reinforcement plate under my engine. I decided to do it during the Xmas break such that I did not feel the Monday-is-coming daily driver pressure. I was not a picnic getting it out! My plan was to simply use an electrical impact wrench, apply pressure to the bolt with an object (screwdriver, etc.) and pull it out. But this was a no-go. I ended up cutting the head of the bolt off with a Dremel 1 inch cutting blade. Slowly but carefully to avoid damaging the plate and other stuff. That worked. When I got out the thread that was left in the frame, I put it in my vise and tried to turn the nut. I did not move! I was really really stuck on! No hope at all getting it out. So, really spend the few bucks, plan it out and put -new- clips and bolt in. (bolts 31106772199 x 5 & clips 3116779393 x 3) I put a bit of good grease on the bolts when I put the plate back on to avoid corrosion and make the loosening process easier in the future. 56 Nm of torque on the bolts. Here are some pictures of the bolt removal process:
The situation with the spinning bolt. I was able to take all other bolts out (despite the driver side rear bolt giving me the same trouble for a while, but with some trying it actually came out) and with enough play in the offending bolt being loose, I was able to turn the reinforcement plate such that the clip insertion access hole became accessible.
The carnage after carefully cutting the head off the bolt. The washer saved the plate! And thank God for Dremel tools and 3 diamond blades later! Note that the nut retaining pieces of the clip completely broke off! No wonder it spun.
The difference between the old clip that came out of the car and the new clips that went in. Clearly BMW made a design improvement!
The new clip installed in the frame. Note there are 3 clips as opposed the 2 I reported before! TIS showed only 2, not 3. The two rear bolts have clips and the front middle have a clip. I replied them all and used new bolts in all 5 locations for my 2008 6MT car. I say this because my bottom cover is different from the pictures above in
@douglas_ngo situation. Not sure if the LCI related or SMG versus MT6.
And then finally I was able to replace the O2 sensor on the driver side. This should have taken 1 hour. LOL! Here is the old and new sensor, side by side.
I am not sure if the replacement will help my problem of a reoccurring P0114D fault. It -ONLY- happens on very long (1 hour +) drives, two in a row. Out and back, e.g. the two drive cycles that are needed to set the CEL for this fault. I haven't gotten out that far yet. (I might have to go see
@jcolley next week for that purpose!) It will -not- happen on my daily commutes for months! Just long spirited drives. If not, it will be time for a smoke test, to see if we have small leaks. Or a new catalytic converter. Which really means: Straight pipe this puppy and get a tune?