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BMW Check Engine – Service Engine Soon Light & Fault Codes

March 19, 2010

This answer is applicable for many BMWs in addition to the one listed below.

Q
My SERVICE ENGINE SOON light came on. The manual says that something is amiss with the emission control systems. Can I diagnose and repair this?

A
The CHECK ENGINE light (or SERVICE ENGINE SOON) will only come on when the engine management system has recorded a fault. In order to know what the fault is, we must use a code reader tool to check the stored fault(s). We do offer a fault code reader and reset tool that you can use to check the codes. The tool will also reset the oil change and inspection reminders for most earlier mo0dels. Once we know what the codes/faults are, we can work on addressing them.

Check out the following links to the Spring 2005 and Winter 2007 issues of our Bavarian Autosport Fast Times Newsletter, for articles on using the fault code readers and understanding the fault codes.


Click here for the Spring 2005 Fast Times:
http://www.bavauto.com/newsletter/2005_n205_newsletter.pdf


Click here for the Winter 2007 Fast Times:
http://www.bavauto.com/newsletter/2007_n107_newsletter.pdf


Click here for fault code readers & reset tools (please be sure to ID your BMW model):
http://www.bavauto.com/se1.asp?dept_id=375

Steve wrote back:

My code reader just came in.  It tells me two codes (in table #20);  code #2882 (mixture prep, bank-1) & code #2883 (mixture prep, bank-2).  Do you have any suggestions?

A
The first step in diagnosing the fault codes (especially if the engine seems to be running fine) is to clear the codes and see if they return.  If the codes do not return, they may have been left from a prior issue (never cleared) or may have been errant short-term issues that are not current.  If the codes do return, we will begin to address them.

These codes are indicating a fuel mixture problem.  Since the codes are showing for both banks (bank-1 = cylinders 1 through 3 , bank-2 = cylinders 4 through 6), the fault will be something that affects all of the engine’s cylinders, as opposed to something that would be localized to a specific cylinder (or cylinders).  A common source for codes like this would be vacuum leaks in the intake, crankcase ventilation and vacuum systems.  We should do a complete inspection of all of the rubber boots, bellows and hoses that carry air.  The engine in your Z4 (M54 engine family) has a common issue with vacuum leaks and clogging of the crankcase ventilation system (multiple hoses, an oil separator and check valve).  Since the majority of this system is not readily visible (it’s under the intake manifold), I would suggest that you have the intake system tested for leaks using a “smoker”.  This is a machine that injects smoke into the intake system, under a small amount of pressure.  The smoke will leak out in any areas of leakage.

If no leaks are identified,  we will diagnose some other areas.

3 Comments
  1. STEVE TIBERIO permalink

    I WILL RESET THE FAULTS AS DIRECTED.

    I WILL CHECK EVERYTHING VISSIBLE AND TRY TO IMPROVISE A SMOKE MACHINE.

    I SHOULD ALSO MENTION THAT THE MPG IS DOWN ABOUT 20%, (27 MPG TO 22 MPG), SUGGESTING A RICH MIXTURE.

    THANKS,

    S.TIBERIO

  2. suzanne fontenot permalink

    My service engine soon light came on while I was driving and the car started riding “rough”…loss of power…what could it be?

    • In order to start any diagnosis, we will need to read the stored fault codes. You will need a code reader for this, as noted above. Without checking the fault codes, we could end up spending diagnostic time and replacing parts that may be unnecessary.

Comments are closed.