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No engine management light

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by PeterW1966, Nov 7, 2020.

  1. PeterW1966

    PeterW1966 New Registration

    Likes Received:
    Nov 7, 2020
    Your Mercedes:
    SLK 230 R170 2004
    Hi All,

    My first post here. I have done some extensive searches but apologies if I missed something already posted.

    I bought a 2004 SLK 230 (R170) about a year ago. At the time (foolishly) I had not spotted that the engine management light was not coming on when the key was in the IGN position. Once I spotted this I checked for fault codes with a code reader and nothing was showing up. The car runs well with no obvious faults. I also pulled the connector off the MAF sensor (which I understood should trigger the engine warning light) - nothing.

    Whilst I thought it was unlikely that the bulb had blown I bought a new bulb and today I went about changing it. The dash removal was surprisingly straight forward, which was a relief. However, I checked the engine management bulb and it looked fine. I replaced it with a new bulb and still no light with the key in IGN position.

    Now here is something that worries me even more. I also changed the front discs and pads today. The pads were very worn, to the point where the wear sensors on both sides were clearly worn through (showing metal). However, I have not had a warning light come on for this. The brake wear warning light does come on with the key in IGN position (along with all warning lights apart from engine management light). They all go out once the engine is started.

    So, I am trying to find out if there is some know "bodge" that a previous owner may have done to hide an engine management light triggering fault? Or is there a known issue that could effect all warning lights? I did try pulling the connector off the brake fluid reservoir and this didn't trigger a light, but maybe this is normal.

    Any ideas or suggestions will be gratefully received.

  2. clk2000

    clk2000 Active Member

    Likes Received:
    Jan 31, 2019
    Your Mercedes:
    Hello Peter,
    If it were me, I would be looking possibly towards an earth wire on the instrument cluster maybe cut ? The one that feeds the warning lights would knock them all out whereas to tamper with each positive wire from each sensor would be a major job. If several lights are out, for my money, that is where I would start.
  3. Botus

    Botus Senior Member

    Likes Received:
    Jul 29, 2014
    Your Mercedes:
    its mandatory the warning lights come on and go through self check to get an MOT these days

    find another and check things against that

    and in the mean time shine a torch in the hole and see if the eml glows.... the bulb fiddle is harder than a bit of paint or cardboard
  4. matthew k

    matthew k Senior Member

    Likes Received:
    Feb 4, 2015
    Winchester Hampshire
    Your Mercedes:
    2005 320 cdi Sport 7 seat estate
    The lack of codes is a good thing, if I remember rightly that engine can suffer from oil emigrating around the loom, maybe CSP sensor failure too? I had one in a manual CLK, wish I'd kept it TBH.

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