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SMG Error codes

Discussion in 'E46 (1999-2006)' started by bernstra, Aug 19, 2011.

    bernstra guest

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    New member here with a 2004 330i with the SMG transmission that I've had for about 2 years now. Fun car to drive and I like the idea (and the functionality when it works) of the SMG, but recently it has been leaving me stranded. Driving along and get the audible beep once, then again about 10 seconds later, and then the SMG fault light on the dash comes on. According to the manual, the beeps are an indication that the transmission is overheating (manual says to stop or increase pull-away speed so the system can cool down!), but we cannot find a temperature sensor anywhere on the tranny or on the SMG hydraulics. After the fault light comes on, the car will stay in gear until I slow down and then it gets stuck in neutral (if I'm lucky, stuck in gear if I'm not). After about 10 to 30 minutes, it will start up again and behave normally for awhile. We've tried bypassing the hood switch (common problem supposedly), and we just replaced the SMG relay back in June (also common problem supposedly) with the updated relay...those didn't fix the problem.

    Today, we pulled the following codes when it would not start after being driven for awhile: 4F72 and 4FB4. Does anyone know what the 4F72 code is? I cannot find any info on it.

    Thanks in advance,


    rich235 guest

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    I looked through all the codes in my Bentley which covers your year and series and I dont see the code.
    • Member


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    SMG Faults 4F72 and 4FB4

    Hello Robert,

    There is an updated wiring harness and relay for Fault 4F72. Although it is possible to have a failing pump, this fault can be stored as a result of the voltage drop from the factory relay and connector. I would recommend the above repair first. You will also need to have the gearbox "teach in " procedure performed so that it can readapt and relearn new values. For fault 4FB4 it can be set due to Fault 4F72 being present since it is a monitoring fault.

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