How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask BMWDoc Your Own Question

BMWDoc
BMWDoc, Independent BMW shop owner
Category: BMW
Satisfied Customers: 6426
Experience:  20 years of experience working with BMW's. Independent European shop owner and technician.
14582033
Type Your BMW Question Here...
BMWDoc is online now
A new question is answered every 9 seconds

BMW 528i: I have a 2000 BMW 528i. Recently replaced secondary

Resolved Question:

I have a 2000 BMW 528i. Recently replaced secondary fan motor, valve, thermostat, water pump and head gaskets, After driving approximatly 100 miles and 2 cold starts the check engine light is back on with a secondary fan motor code. Assumed faulty part and replaced new secondary fan motor . check engine light came back on after second cold start. Where do i look for secondary problem that might be the cause?
Submitted: 1 year ago.
Category: BMW
Expert:  BMWDoc replied 1 year ago.

BMWDoc :

Hello, I'm Jason. I will do my best to answer your question quickly and accurately using the information you have provided.

BMWDoc :

Is the code you're getting a P0411?

BMWDoc :

or 491/492?

Customer:

Repair shop did nor say the code number only the secondary fan motor error code would not reset after the drive cycles.

BMWDoc :

Hmmmm. This makes it a little more difficult to try to diagnose remotely....

BMWDoc :

So, you're not doing your own work, correct?

BMWDoc :

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

Customer:

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

BMWDoc :

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

BMWDoc :

that would be the first thing I'd need to know. And if so, is there vacuum being applied to the combi-valve?

Customer:

Is there someting else like a vacumn hose or sensor connection that would show the same code but mask itiself?

BMWDoc :

and if so, are there any pressure leaks?

Customer:

Been pressure tested no leaks

BMWDoc :

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

Customer:

What are some possible sources of the vacuum leak.

BMWDoc :

Now, let me ask this before flooding you with information. Are you aware exactly how the secondary air system works?

BMWDoc :

I just need to be able to gauge my responses here

Customer:

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

BMWDoc :

Ok, good. Do you mind if I link you to a PDF first, so that my explanations and possible causes make more sense?

BMWDoc :

I'll give you that actual page numbers here

BMWDoc :

http://www.bmwmotorsports.org/BMW_docs/m54x5.pdf

Customer:

Sure Found site looks like table of contents

BMWDoc :

ok, scroll down to page 35

Customer:

does not have page numbers only categories not on right site?

BMWDoc :

page numbers are at the bottom right of each page

Customer:

Think I found page 35 show picture of cylinder with the secondary fan motor injection air filter . Right page?

BMWDoc :

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

Customer:

Found it

BMWDoc :

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

BMWDoc :

one moment though....need to step away from the keyboard

Customer:

Go ahead and post your thought and I can look at the PDF for reference. Will stand by.

BMWDoc :

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

BMWDoc :

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

BMWDoc :

the shop is going to ned to verify the integrity of this vacuum hose. I have a feeling that is the root problem here

Customer:

Additional thought replaced both the upper and lower cam sensors

BMWDoc :

intake and exhaust cam sensors?

BMWDoc :

that won't affect this

BMWDoc :

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

BMWDoc :

However, that's pretty rare on these

Customer:

Thanks this is a start better than when I started. Beginning to think it was possessed and needed an exorcism.

BMWDoc :

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

BMWDoc :

If you need to catch me for any other questions on your car, please bookmark this link

BMWDoc :

http://www.justanswer.com/car/expert-eurodoc/

BMWDoc, Independent BMW shop owner
Category: BMW
Satisfied Customers: 6426
Experience: 20 years of experience working with BMW's. Independent European shop owner and technician.
BMWDoc and 4 other BMW Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
< Last | Next >
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
 
 
 

Meet The Experts:

 
 
 
  • Roger

    BMW Master Tech

    Satisfied Customers:

    2906
    10 yrs. experience as BMW Master Technician, shop foreman and dealer.
< Last | Next >
  • http://ww2.justanswer.com/uploads/Guest/2008-02-15_191551_avatar.jpg Roger's Avatar

    Roger

    BMW Master Tech

    Satisfied Customers:

    2906
    10 yrs. experience as BMW Master Technician, shop foreman and dealer.
  • http://ww2.justanswer.com/uploads/EU/eurotec/2012-6-11_13153_mpjaphoto.64x64.JPG Marty's Avatar

    Marty

    ASE Certified Technician

    Satisfied Customers:

    406
    ASE & Bosch Certified Master Tech. Over 30 years experience.
  • http://ww2.justanswer.com/uploads/DA/dansciol/2012-7-7_16177_danpic.64x64.jpeg bimmaster's Avatar

    bimmaster

    BMW Technician

    Satisfied Customers:

    1817
    3 years dealer experience, master bmw tech
  • http://ww2.justanswer.com/uploads/bmwmaster/2009-05-09_062111_avitar.jpg Sam's Avatar

    Sam

    BMW Master technician

    Satisfied Customers:

    1043
    BMW S.T.E.P. graduate, 10 years BMW dealership experience
  • http://ww2.justanswer.com/uploads/hondatrx450/2010-01-18_231606_stuff_092.JPG mike's Avatar

    mike

    BMW Technician

    Satisfied Customers:

    694
    bmw master tech ase certified
  • http://ww2.justanswer.com/uploads/CA/caprio23/2011-12-13_155550_20111213105344.64x64.jpg Anthony's Avatar

    Anthony

    BMW Technician

    Satisfied Customers:

    628
    ASE Master Automobile Technician with over 20 years exp. in this field.
  • http://ww2.justanswer.com/uploads/bmwbum01/2009-12-28_205712_germany2000.jpg Thebmwbum's Avatar

    Thebmwbum

    BMW Foreman

    Satisfied Customers:

    533
    31 years BMW Experience