BMW Repair Questions? Ask a Mechanic for Answers ASAP
Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.
Is the code you're getting a P0411?
Repair shop did nor say the code number only the secondary fan motor error code would not reset after the drive cycles.
Hmmmm. This makes it a little more difficult to try to diagnose remotely....
So, you're not doing your own work, correct?
There are some pretty specific steps and pieces of information I'd like to know along the way, and that's often tough to relate 3rd party, if that makes sense
correct. But the problem seems to have the shop frustrated as they can't seem to figure it out new fan motor and new valve yet will error out after drive cycle complete usually 80-90 miles and 2 cold starts error returns
Ok, so I'm going to assume that the error is a low-flow detected error. I do understand that they replaced these parts, but another thing that I don't know right now is if the secondary air pump motor even starts up during a cold start
that would be the first thing I'd need to know. And if so, is there vacuum being applied to the combi-valve?
Is there someting else like a vacumn hose or sensor connection that would show the same code but mask itiself?
and if so, are there any pressure leaks?
Been pressure tested no leaks
sure, if vacuum isn't actually being applied to the combi valve, then secondary air flow won't make it into the exhaust stream, and when the readiness test is performed by the engine computer, a fault will be detected because the primary oxygen sensor won't show enough lean deviation during the pump cycle
What are some possible sources of the vacuum leak.
Now, let me ask this before flooding you with information. Are you aware exactly how the secondary air system works?
I just need to be able to gauge my responses here
Basic knowledge but not a tech by any means . Looking for some logical questions to ask the shop have you looked here or there maybe some not so obvious places to look
Ok, good. Do you mind if I link you to a PDF first, so that my explanations and possible causes make more sense?
I'll give you that actual page numbers here
Sure Found site looks like table of contents
ok, scroll down to page 35
does not have page numbers only categories not on right site?
page numbers are at the bottom right of each page
Think I found page 35 show picture of cylinder with the secondary fan motor injection air filter . Right page?
Perfect. Yes, so that picture just shows how secondary air goes into the system to heat the cat up faster. That port is actually cast into the cylinder head. Does that make sense? If so, scroll down to page 37
Ok, so there's all of the information on what the SAI system does. Now, you can read through that now, and I can hold the chat open while you do, or I can post my thoughts on what might be wrong, and you can reference that PDF later on
one moment though....need to step away from the keyboard
Go ahead and post your thought and I can look at the PDF for reference. Will stand by.
So a few things happen during a cold start. Secondary air pump starts, vacuum valve behind the manifold on the driver's side opens, to apply vacuum to the port on the combi valve, which then opens to allow pressurized secondary air into the exhaust stream
now, what happens a lot when either valve cover gaskets are replaced, or cylinder heads are removed, is that the small vacuum line from the vacuum valve to the combi valve gets broken or pinched, which then doesn't allow the combi valve to open
the shop is going to ned to verify the integrity of this vacuum hose. I have a feeling that is the root problem here
Additional thought replaced both the upper and lower cam sensors
intake and exhaust cam sensors?
that won't affect this
So, if the SAI system is functioning perfectly, no vaccum leaks, pump starts up fine, combi valve opens as it should, then there is a good possibility that the SAI passages in the cylinder head itself are carboned up, which will require head removal
However, that's pretty rare on these
Thanks this is a start better than when I started. Beginning to think it was possessed and needed an exorcism.
I'm ridiculously familiar with secondary air faults on all German cars. Glad I was able to help you out on your first foray into JustAnswer
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