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Thread: D4 Coolant Level Sensor

  1. #1
    Join Date
    Sep 2013
    Location
    Sydney
    Posts
    70

    D4 Coolant Level Sensor

    I recently had my mechanic advise that the Coolant Level Sensor is faulty and I get a message as such on the dashboard display. He said he could replace it but itís not essential so I held off given I had other servicing costs.

    So question : is this an easy DIY replacement? (the error message is becoming disconcerting)
    If so, whatís involved and any recommendations on where to source?
    TIA!

  2. #2
    Join Date
    Mar 2018
    Location
    Perth
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    332
    I'll just say the coolant level sensor is the only way you're going to know you've had a catastrophic coolant loss before you toast the motor. As the coolant temp sensor sits in the water, once the water is gone it takes a long time to register the increase. In the mean time bad things happen.

    In the D3 we replaced the coolant bottle as a whole unit.

  3. #3
    Ean Austral Guest
    On the D3 , The float gets coolant logged and sinks tripping the warning . Easy to replace the whole bottle , so would assume the D4 suffers the same issue .

    roverlord sells a good priced replacement.

    Cheers Ean

  4. #4
    Join Date
    Oct 2012
    Location
    Perth
    Posts
    919
    Quote Originally Posted by Ean Austral View Post
    On the D3 , The float gets coolant logged and sinks tripping the warning . Easy to replace the whole bottle , so would assume the D4 suffers the same issue .

    roverlord sells a good priced replacement.

    Cheers Ean
    Interesting, I have seen this reported many times but not had the problem (yet) MY08. Same supplier as the dodgy big end bearings perhaps.

  5. #5
    Join Date
    Mar 2016
    Location
    Perth
    Posts
    1,718
    I bought a generic replacement bottle and it came with a faulty sensor of all things. In the end I replaced the new aftermarket sensor with my original one. No issues since. I only replaced the bottle as I was doing a coolant flush
    2010 TDV6 3.0L Discovery 4 HSE
    2007 Audi RS4 (B7)

  6. #6
    Join Date
    Jan 2014
    Location
    Perth Western Australia
    Posts
    1,444
    D3 / D4, both can have the same issue.

    *The sensor can fail if its newer.
    *Older as previously mentioned, the float gets coolant logged and sits on the bottom of the expansion tank.

    I recommend getting it replaced, as others have said.
    Regards
    Daz


  7. #7
    Join Date
    Apr 2011
    Location
    Coffs Harbour
    Posts
    452
    I had a coolant low warning come up whilst driving on the highway. I pulled over very quickly and shut down. When I lifted the bonnet the level was normal, what a relief.
    Overflow bottle replaced which also gave me the excuse to clean out the intake manifold and replace the plastic coolant manifold as well.
    2012 Fuji White 3.0 D4, Rear view camera, Hi-line sound, E-diff, Xenon lights, ARB winch bar, Lightforce 240 50w HID. Brads sliders.

  8. #8
    Join Date
    Sep 2013
    Location
    Sydney
    Posts
    70
    Thanks to all.. Iíll look to purchase a new coolant bottle

  9. #9
    Join Date
    Dec 2009
    Location
    SW WA
    Posts
    289
    I was getting the low coolant level after changing/flushing my coolant, the messages were every time i drove the car despite the levels being correct.

    There is a video (on the net) showing that the float will sink in water or float in coolant, suggesting that the float is in fact a hydrometer as well as a level warning.

    Anyhow, when refilling mine after many flush cycles I only put in 5 liters of coolant concentrate then about 3 liters of water, that was it, even after bleeding it was full.

    With a system capacity of 11.8 liters I needed 5.9 liters of coolant concentrate to get the correct mixture. By sucking out 1 liter and replacing it with concentrate the low coolant warnings are gone, for last week at least. If you were refilling with premix you would have no hope as the system does not fully drain, at least not when draining as per the workshop manual.

  10. #10
    Join Date
    Jan 2014
    Location
    Perth Western Australia
    Posts
    1,444
    If that was the case, replacing the expansion tank with a new one would make no difference to the low coolant warning. Yet after replacing 50 million of them I've not had this issue return.

    I use premix from the oil supplier as I believe their mix is going to be more accurate than trying to mix it in the vehicle.
    Also I know there are workshops out there that simply use water to mix which negates any spec coolant has.
    Too weak or too concentrate and coolant is corrosive.
    Draining and refilling every 2 years or so will keep it at a good mix.
    Using a accurate hydrometer is the only real way to check.
    Regards
    Daz


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