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Coolant Level Sensor

Discussion in 'E39 (1997-2003)' started by TeamStowell, Feb 8, 2009.

    • Member

    TeamStowell We love driving!

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    I'm getting the warning but my level appears to be OK. Is there something else to check or do I just replace the faulty sensor? If so, how difficult is it?

    Thank you
    • Member
    • Technical Service Advisor

    mooseheadm5

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    Usually a faulty warning is a bad sensor. It is under the tank and pulling it will not drain any coolant. However, once you pull it, you will need to test it. Often the sensor itself is fine, and the tank is what is broken. If this is the case, replace your tank immediately.

    richtell guest

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    Just recently, on a few very cold days ( for Florida, mid 30s), the check control came on "check coolant level" after turning off the ignition in both my E36 BMWs, The coolant level was OK in both. Is this a circumstance that would prompt testing the sensor?
    The timing of this post is good, because I am about to install a new radiaotor in my 99 M3 with 96K miles and will change the sensor at the same time if necessary.Would you arbitrarily change the sensor at this mileage?

    H Richter
    Tangerine FL
    99 M3 conv.
    97 M3 sedan
    • Member
    • Technical Service Advisor

    mooseheadm5

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    Replace the sensor only if it is bad. It is a simple reed switch, so when the coolant is full, the circuit is complete. Just test it with an ohm meter.

    richtell guest

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    Thanks for the info
    • Member

    TeamStowell We love driving!

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    Yes, thank you Paul. I was just about to ask how to test the sensor.

    More Rep Power to you for your assistance!!

    ViolinARC guest

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    I had this exact same problem on my '89 750iL and on my '00 540iA. From my experience, the sensor is merely a float on a stick in the expansion tank. The float gets dirty over time, sticks and no matter how many times you bleed the system...the error continues. I replaced the one on my 750...problem solved. I replaced the failed expansion tank on my 540...problem solved. Even when the level in the expansion tank (540) is low, I don't get any CEL. Go figure...
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    459913

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    i have the same issue on a 540i with only 96000 miles. is that a normal issue?
    • Member

    dmmai

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    .
    459913 wrote:
    Same song, 38,000th verse. 540i with just 73,000 miles. Check Coolant Level comes on at various times. Coolant level is fine.
    Is this "normal" ? ?
    Of course it's not "normal" ... it's just a BMW.
    Everything relating to the cooling system on a mid-years BMW is simply failure in progress. Part of the joy of driving.
    Fortunately, the fix isn't a difficult DIY. Don't be shocked by the price of the replacement parts. I've been told by a reliable source that they are made of pure, solid 24k gold, plated in platinum and festooned with precious gems. Worth every penny......
    .

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