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Discussion Starter #1
Hello,

Got another check engine light, pulled the code and it was code P0411, did a search online and this is what came up. P0411 Secondary Air Injection System Incorrect Flow Detected. I had also noticed some engine "shuddering" in high gears at low rpms between 1800-2500 under heavy accelaration. Is this the dreaded carbon build up problem? I had thought it was the MAFs, then I did the fuel consumption test and got readings of approx 120 liters per hour in 1st gear, 2nd gear it wouldnt go higher then 110. At idle it reads 0. I had cleaned the MAF's about a week ago but the cleaning didnt seem to have fixed it. So where do I start? Any help would be greatly appreciated and thanks in advance.

:3:
 

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Read up on the carbon buildup thread.

Try running a few bottles of STP Complete System Cleaner and see if that helps.

Check if the secondary air injection system might be covered under state laws regulating mandatory extended warranties.

Sometimes the car will trigger the Secondary air system code by mistake.
Clear the fault code, and see if it returns.

The secondary air injection is only used during cold winter starts to heat the catalytic converters faster. It is of no imporance to any other aspect of the car than its smog-test legal status, and of course its emissions right after a winter low temp start.

When was your car built?

The high gear - low RPM shudder is found in all E39 M5s. Not to worry.
Go for a ride with a fellow M5 owner and compare if you want to be absolutely certain the shudder you have noticed is the normal one.

David
 

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Can you include some basic info about your car ala the Carbon Build-up Poll thread? I'm trying to collate information on this issue... sounds like you could have the C-word... :(

Cheers,
 

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a little more data might help too. how many miles, have the mafs been replaced before. You mafs/fuel data is not perfect, 110 in second is low, and it certainly should not be 0 at idle. Usually just under 2L hour at idle, about 2.4ll/H with the a/c on is what i usually see. Sometimes cleaning mafs doesnt work, DavidS has a group buy on some mafs that are a good price.
Mike
 

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Please read the thread FAQ on Carbon Build-Up. I have the same code coming up. I belive it is the dreaded C-word. Basically your pre-cat O2 sensors are telling the computer that they are not detecting enough oxygen on COLD start ups, which is probably related to carbon build-up blocking the ports and channels that the smog pump (secondary air injection system) send air in through the heads. If you would please try and move your discussion and quesitons to the FAQ on Carbon Build-Up thread so we can develop our M5 tribal knowledge and possible figure out possible solutions and the root cause of this problem.

Luke
 

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Are you sure you're not testing litres of fuel per kilometer instead of per hour? The figure is engine speed/load dependant and shouldn't vary with gear... Press the left button once when you're in the test.

Andy
 

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Discussion Starter #7
Thanks for all your help. Sorry it took me a while to respond as I was away for a few days. The car is an '00 with a build date somewhere in '99 will double check tomorrow and follow up. Car has a little over 90k miles. Running on 10 w60 oil with no oil consumption. I cleared the code and the SES light came back on after a few cold starts. I have just read the fix that LLcoolM5 has done on his beast, it was very informative and extremely helpful, I suggest anyone having similiar problems should read it, it can be found here :

http://www.m5board.com/vbulletin/showthread.php?t=57536&page=5

Hope this helps and thank you all for your advice :cheers:!
 

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IMMMPRESSED said:
Thanks for all your help. Sorry it took me a while to respond as I was away for a few days. The car is an '00 with a build date somewhere in '99 will double check tomorrow and follow up. Car has a little over 90k miles. Running on 10 w60 oil with no oil consumption. I cleared the code and the SES light came back on after a few cold starts. I have just read the fix that LLcoolM5 has done on his beast, it was very informative and extremely helpful, I suggest anyone having similiar problems should read it, it can be found here :

http://www.m5board.com/vbulletin/showthread.php?t=57536&page=5

Hope this helps and thank you all for your advice :cheers:!
If you truly have a blocked Al secondary air line, you would be the first car with on reported oil consumption and carbon build-up. Please try to report back to the carbon build-up thread if you have any plugged lines. Pictures would be great! BTW, it is not that hard, just be patient and take you time and you can easily do it (clean the Al line). Try to PM me if you get stuck.

LL
 

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My 2cents. Forget about generic OBDII codes/readers and pick up a Peake Research tool. It will give you BMW-specific (and engine-specific for various BMW's) codes with a lookup table. I have found this info to be vastly more informative then generic codes. I haven't used my generic reader since I bought the Peake tool.

:cheers:
 

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www.peakeresearch.com

It comes in a nice case and can be stored in the car as it is pretty small.

:cheers:
 
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