tmlesko said:
Please read the other 'carbon build-up' thread entitled:
"FAQ on Carbon Build-Up Issue (First Attempt)"
There is a wealth of discussion and detail here, including a diagram of the secondary air system and lots of photos from LLCool on page 5 of 6. I just cleaned my secondary air pipe and installed a new valve, changed the belts while I was there. Did not have to remove the radiator as LL describes. Still took me over 6 hours. I will post my information on that thread. My secondary air pump was working, I could hear it running when the car was cold so I did not change that. I think your dealer jumped to conclusions. I will clear the codes and hope that I am good for another 48K miles.
Tom L.
Readers (and TetherM5): I would echo Tom's referral to the "FAQ" thread which discusses this issue in detail. The evidence to date suggests that the full $8000 cleaning procedure may not be necessary, and that simply clearing the secondary air pipes may be sufficient to resolve the issue. Tom's procedure is the third example we have of this 'intermediate' approach to the problem. It remains to be seen whether the SES light stays off in Tom's car. LLCool's problem appeared to be resolved (at last report) after several weeks of cold starts. In LLCool's case, the pipes were completely clogged, which obviously would have triggered the fault. There is a third example from another board member (who's name escapes me at the moment) who had an independent garage perform the procedure which resolved the fault. Unfortunately, for some unknown reason, his secondary air pipes were again completely clogged a year later. It was speculated that his secondary air shut off valve might be leaky making his secondary air system suseptable to carbon condensation. I'm not aware of any follow up on this possibility.
To summarize the information to date from the Carbon Buildup Poll, there is not single example of a non-US car that we are aware of experiencing a carbon build up problem. In the US, we have seen the issue in as early as 17,000 miles in a '01 MY (Hawaii), and we've seen high mileage 99-00 cars that have not had the issue. We've also seen the issue with almost zero oil consumption, and we have an example (UK car, ~60k mi) where there has been no carbon issue despite very high oil consumption (1 L/500 mi) and predominantly low speed stop-and-start driving (conditions one might associate with high carbon deposits). Basically, the evidence points away from oil consumption and driving habits as the key factors in the problem. The association with the problem with 99-00 cars may be simply that this group has higher mileage on average than '01-03 cars. It seems reasonable that carbon build-up tendencies will in most cases manifest as a problem as the mileage piles up. The question of regional/geographic differences in gas quality may be an important variable, but we have no substantive data on this.
TetherM5, my recommendation is to make a lot of noise with your BMW dealer and BMWNA, and pursue a goodwill repair. If this doesn't work, consider a secondary air pipe cleaning procedure, which may well fix the problem at a fraction of the cost.
Good luck and keep us posted!
Cheers,