SES light is on, throwing a No. 2 O2 sensor fault (after the cat). Dealer replaced O2 sensor. Still throwing code. Dealer determined the sensor isn't being powered up,but still can't figure it out. Any ideas? The problem first occurred after a full throttle launch.

They are guessing it might be the DME and want to replace. I'll end up losing my tune if they do that (no, it's not the tune which has caused no codes since installed 2 years ago)

 

wires good from 02 to dme?

 

They said they they checked out ok, but earlier in the week they said they found excess resistance overthe length of those wire. Can't be certain what to believe.

 

If there is excess resistance in the power wire, a new DME won't fix it.

You need to find where the resistance is coming from. Broken sheathing and corrosion? Corroded connector terminals? Its has to be something.

 

Still no progress. Dealer still has the car. Fortunately, I got a loaner. Warranty company didn't want to cover the DME since they claim BMW has to warrant under the 80k,8yr emmissions system warranty. BMW trying to figure out if the DME is really included under that federally mandated warranty. Dealer still claiming wiring and connections ok, and it is the DME not sending any signals to the O2 sensor. According to them, "that is probably it".

 

As I suspected: Dealer installed new DME, and problem still isn't fixed. Any thoughts?

 

What's the code?

 

They won't tell me the code. After 5 weeks they still haven't fixed it. They tried a smoke test at the very beginning to find a leak in the intake or exhaust. Found nothing at that time. They then tried to replace the computer under the 80k emissions warranty and BMW is making them do a whole bunch more tests before they provide a new computer under warranty. Again this week they did another smoke test, miraculously found a leak this time and are charging me $500 to replace a leaking tube to the intake. Dragging their feet at this time. I'm guessing the repair didn't fix anything. Note several posts above that they identified a bad signal going to the O2 sensor from the computer. At some point they'll replace the computer. I still think the whole problem is a bad MAP sensor. I'm surprised the dealer is allowing me to hold on to the loaner for this long.

 

"leaking tube to the intake" see if you can find out which tube.

This is a issue with SPUD, yes? If so, the upstream MAP could be the problem. Over the last 4 + years, possibly since new, there has been a come & go kind of flat spot with my car. It's a long story....

 

Yes, issue is with SPUD. I'll find out what tube.

 

FYI

After six weeks (and 2 or 3 smoke tests), they finally figured out that it was connections to the intake duct (below the IC) that were leaking. The tube to the boost pressure sensor was actually blown out of the connection, erroneously telling the DME that the SC was under-boosting.

 

Glad you got the issue sorted.

I had the same problem, it took a couple of disassemblies before I could find a crack in that tube. The dealer replaced the upstream O2 4 years ago. There was always a flat spot, possibly since new. Not now. They, at the time, said, new injectors would solve the problem, not.