Oxo Sensors keep failing on my beemer!

Hi All,
I was just RE-reading through all the earlier responses and I realized I made a big typo in one of the codes. My first code - P0491 - was correct. My second code - “P0942” - was wrong; it should be P0492. But my description of that second code was still correct “Secondary Air System (Bank 2).” Perhaps you figured that out and were too polite to mention it.
Does that change anything in the comments you have already provided?

My car does not seem to be making troublesome noises - at least not yet! I drive it to work every day.

We recognized the typos with the trouble code. It caused no confusion. You still need a mechanic who can troubleshoot the oxygen sensor CIRCUITRY. Resistances and voltages need to be checked (not more parts changed).
Likewise, all the circuitry for the AIR pump needs thoroughly checked out. This DOES mean using a multimeter to check electrical values.


Oh Woe is me!

This will be my final update until after Christmas.

I took my car back to the mechanic last week - for the fourth time!!! He kept my car for 3 whole days this time. I provided him with a print-out of all the pertinent comments from this online “discussion” to give him ideas on what to check and do.
I picked up the car Friday evening. The owner/mechanic had gone home. I think he was avoiding me.
The young shop MANAGER gave me the “invoice” - but there was no charge. It showed that the owner/mechanic did the following:
“Cleaned EGR Valve; Lube air pump and clean; cleaned exhaust combustion chambers.”

The young shop manager added: "He has run out of ideas."
I drove off feeling very frustrated. The “service engine soon” light was out, but I’ve seen that before.
Saturday I did not drive the car at all. It sat in my driveway.

Sure enough, Sunday afternoon, I got in the car and my heart sank when that “service engine soon” light came on again as I started up the engine. And it is still on.
I am going to have to put this off until I get back from my trip for Christmas. I am heading about 175 miles north and I just pray that the round trip will not do damage to my car.
When I get back, I may have to bite the bullet and pay the BMW dealership to diagnose the problem.
But honestly, I have little faith in them as well, based on prior experiences. 3 years ago they fixed a leaky back door (vapor lock seal - “not seated properly” ?? the replaced it) but the problem is back with a vengeance. Every time it rains, I get a soaking wet floor behind the driver’s seat! Also - last year, my car died, but the BMW dealership insisted the battery was fine. They said I needed a new alternator. That cost me a bundle. 2 days later, my car died, and I had it towed back to the dealership. They told me the battery was dead and had to be replaced. (I was furious; how could a battery be “perfectly good” one day and “dead” 2 days later?)

So you see - I’ve had pretty rotten luck all around. I don’t trust any of the mechanics.
As for battling to get my money back from this auto repair shop that I used this time, that’s going to have to wait for the new year. I have too much on my plate right now with Christmas upon us.

Merry Christmas and Happy 2010 - and I hope none of you ever buys a lemon like mine.