MPG Gauge acting weird when ignition is off

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  • dowL
    Noobie
    • Mar 2026
    • 5

    #1

    MPG Gauge acting weird when ignition is off

    Hello!

    I've been messing with the cluster for a few days now, and I finally fixed the odometer gears, the tach, and got everything to work. The mpg gauge decided to start acting funky on me, though.

    It first started flicking around from 0 to random numbers, and back to 0 when the car was off. If I turn the ignition on, it jumps back to 0 normally and stays there. Now, it just sits around 8-9L/100km.
    After some testing, I found out that the problem is in the SI Board, since I am lucky enough that my mechanic has a few extra clusters that we could test. I tried about 3 other boards and 7 clusters, and the issue I'm having only happens with the board I was originally using. Other boards have other problems, so they're not quite usable.

    Does anyone know what could be causing this? I'm almost 100% sure that everything is fine with the wiring in the car, since the problem goes away when I test another cluster or another SI board. My mechanic recently let me know that after an hour of sitting, the mpg gauge dropped back to 0, and it seems stable for now. Also, when we disconnected the battery, it immediately went back to 0.

    I uploaded two videos of how the cluster is acting, and how the board looks here. I hope posting the link is fine

  • bmw444
    Member
    • Mar 2013
    • 59

    #2
    Have you checked the SI board batteries. They are a common link in many cluster issues.

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