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Engine warning light and wrong ext temp.

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by BurgerDave, Dec 2, 2012.

  1. BurgerDave

    BurgerDave Senior Member

    Messages:
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    Joined:
    Sep 22, 2010
    Location:
    Kent, UK.
    Your Mercedes:
    2007 SL350
    Don't know if these are related...

    2007 SL350 (R230).

    A few weeks ago I noticed the dash was displaying external temps much above reality (for example today it showed 18 degrees). The sensor has not fallen out of it's mount as I can still see it poking through the front next to the fog lamp. Unfortunately my dad died the week before last and so I've had other things on my mind.

    Today, while driving home, the engine warning light came on. No reduced power, no message, just the yellow engine warning light. I couldn't sense anything else wrong with the car. Of course it now stays illuminated each time I start the car.

    I know I need to take it the dealers but I just wondered if anyone might have any suggestions on these faults... for example, does the wrong temp indicated suggest just the temp sensor is faulty or something more serious? Is there any way I can reset the engine warning light (understanding it might come back on) until I can get the car checked following dads funeral?

    Many thanks.
     
  2. andy@pcd-ltd

    andy@pcd-ltd Guest

    Personally i wouldnt take it to the dealers i would find a local indi and get them to look at.

    I have never seen an eml come on due to outside temp sensor but there is always a first for everything.
     
  3. OP
    BurgerDave

    BurgerDave Senior Member

    Messages:
    54
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    Joined:
    Sep 22, 2010
    Location:
    Kent, UK.
    Your Mercedes:
    2007 SL350
    Maidstone Mercedes were very helpful and booked the car in today for a while you wait slot. They had it all sorted in just under 2 hours. It turns out the faults were related. Apparently the ECU takes input from the external temperature sensor to assist with setting the right mixture. It also sort of 'double checks' it against other sensors and as Saturday evening was so cold it saw a difference it couldn't reconcile hence the engine management light.

    The new part, an external temp sensor, was just £13.40 and they charged me that and an hours labour which seemed more than reasonable. All OK now :)
     

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