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'Oil min' light

Discussion in 'A3/S3 Forum (8L Chassis)' started by rustynlc, Oct 20, 2013.

  1. rustynlc
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    rustynlc Member

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    Hi folks done a search but can't find anything related, I have an a3 1.8t 180 bhp (engine code AJQ) basically on a few occasions a symbol for oil level minimum/low has flashed up on my dash, on all occasions iv pulled over switched engine off checked the oil level, which has been fine, iv got back in the car turntable ignition on and the smoke/warning has gone, the icon is yellow and not red, just wondered if anyone has any ideas or tips as to why this is happening, I'm kinda swaying towards thinking maybe the oil is running abit thin and causing the sensor to give false readings but not sure if that is possible, other thought was due to having driven up a long steep hill the first time and down a long sloped gradient the other times, could this be the cause or is there other things I should check? Cheers in advance chaps/lasses
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  2. mark_S3
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    mark_S3 Yorkshire & Humber Events Rep Regional Rep

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    Oil Level sensor??? Underside of Sump. Check connection/condition.
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  3. rustynlc
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    rustynlc Member

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    That's not a bad shout, ill have a look first thing, wonder if there is a way of testing to see if its faulty?
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  4. A4 Quattro Sport
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    A4 Quattro Sport Top Gear

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    1.8T engines are bad for the oil pick up pipe clogging and on occasions the oil pressure is too low. This brings on the red warning light though.
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  5. BENJAMIN
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    BENJAMIN Member

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    Check your bonnet switch. Genuinely.

    Weird but true.

    Shamelessly copied from 'ATCer' on uk mk1v's......

    "Really common problem. Your "bonnet open switch" is not working. It's near the bonnet catch. Usually gets covered in dirt.

    This is how the system works:

    1. The oil sensor is very short and sits under all the oil when the engine is off. It is only designed to measure the oil level when the engine is running.
    2. Engine started, the level in the sump goes down, and now the sensor sticks out of the top of the oil. It can accurately measure the oil level.
    3. Oil gets low, yellow light comes on to warn you.
    4. You switch off engine and the oil once again covers up the sensor completely.

    NOTE: The sensor is unable to tell if you've topped up the oil or not with the engine off so VW came up with a cunning plan!

    They figured that to top up the oil you must open and then close the bonnet. So they programmed the oil light to go out when the bonnet has been opened and closed again. So when the bonnet switch stops working, the yellow oil light will never go out. Simples!"
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Hmm, not so sure about that...

    The oil sensor is ALWAYS fully submerged. It calculates oil level using a heater element and some magic. If the oil level dropped low enough to uncover the sensor, you'd be uncovering the oil pickup too...

    The newer cars which have more advanced oil level monitoring (ie the ones with no dipstick!) have some connection to the bonnet switch, but the older system used on the 8L and B5 A4 etc dont. The bonnet switch in my car broke years ago and went in the bin, and i have never had an issue.
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  7. BENJAMIN
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    BENJAMIN Member

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    It definitely affects mk4 golfs and t4 vans. Don't see any reason why it wouldn't be the same for the 8l.
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  8. ScottD3
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    ScottD3 I want your faulty electronics

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    When I first read this I thought it was all crap and can't work out why they would put that in to it but more I read it and think about it. It kind of makes sense since the bonnet switch is wired in to the cluster.
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I guess the OP needs to answer a few questions then:

    1. Did all this start when the oil WAS actually low?

    2. Does the warning remain there forever, or does it come and go at random?


    Simple fact is the cluster can see the engine is running, and it can see the oil level data coming live from the sensor. If the engines running and the level readings are correct, why on earth would it leave the light on because it didnt think you've opened the bonnet?


    My moneys on a faulty sensor.
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  10. BENJAMIN
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    BENJAMIN Member

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    That is quite logical but vag aren't lol. The light can only be reset by opening and shutting the bonnet. Hence why the op gets out and checks his oil (opens/shutsbonnet) and light disappears.

    I agree it does sound like the op has a faulty level sensor that is triggering the dash light, he is the resetting the warning by opening/shutting the bonnet. The light will come back again when the faulty sensor triggers it and the circle of life continues....
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I wonder if its so the light stays latched on, rather than flickering on and off like the screenwash does?

    And if so, WTF didnt they apply the same thing to the screenwash warning!
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  12. rustynlc
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    rustynlc Member

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    Hi thanks for the replys folks, I'm swaying towards a dodgy sensor now, when I open and close bonnet the light goes out, when it lit up last I switched the engine off left it off for half hour turnt the key and the warning remained, opened and shut the bonnet and it didn't come back on, I'm going to change the oil sensor so will whip the sump off and check the pick up pipe at the same time, is sump removal and pick up inspection an easy job or is it a fiddly job?
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