"Check Engine" Light - Info

I took my 240D to the mechanic today. During the conversations about racing, skydiving, NASCAR, etc., the comment "check engine" light came up.
What I learned was that when you "over-fill" the fuel tank, (at least on the newer MBs) you will get that "check engine" light. He said that when pumping fuel, stop as soon as the pump kicks off. Because there's a gadget that measures the amount of air(?), and fuel and when you keep trying to put more fuel into it, you mess up that electronic gadget's reading. So, he says to STOP PUMPING fuel as soon as the PUMP CLICKS OFF and you will not get that (faulty) "check engine" light. He said he learned that himself. Also several other 'goodies' but not pertaining to MB's.
You who are experiencing this "check engine" may want to observe this with your vehicle, assuming that in reality you don't need to have the engine checked.
Helen
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Did he happen to mention what you are supposed to do once it comes on? That's exactly what happened to me and I cannot get it to turn off. Davehd

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No he didn't, and I didn't think to ask. I just assumed he drove it until it went off. He just said that he never did that again and never again had the light come on. Just my two cents worth: Perhaps a sensitive electronic sensor somewhere got blocked? I dunno. At work we have a copier that often (after an ACTUAL paper jam) will continue to display the message that there is a paper jam. Sometimes just 'going through the motions' (lifting the different lids, doors, drawers, etc., in sequence) will resolve it, but at other times it must have the power shut off for a few MINUTES for the memory to be lost. Perhaps someone can reset - reprogram the electronic memory? I don't know... sometimes automatic programming is difficult to erase. I like the 240D!

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To turn off the CE light, you need an OBD II code reader - It will tell you which code caused the light to come on - If you are lucky, it could be the gas filler cap, but it could also be any one of a number of other and more complex problems - Bad Mass Air Flowmeter, bad Oxygen sensor and so on.
To get the code checked either go to your dealer (<$100) , or in the USA go to one of the chains like Auto Zone or Pep Boys - they offer a free service of checking the code and then zapping it (which the code reader can do). You can also buy your own code reader for $100+.
Good Luck!

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What type of code reader would be the one to use on a 1988 420 SEL? And what will it show? Jerry in Ohio
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You would need an OBD analogue code reader . All cars after 1988 would use that system - From 1996 on they have OBD II which is digital.
A Google search should provide what you need. Here is one review: http://pages.prodigy.net/jforgione/mb_scnrs.html
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Just what I was looking for. Thanks very much. Jerry
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An even simpler solution which works on my w124 ('95 e320te) is to simply disconnect the negative battery cable for a few minutes (10 or so). Just be sure that you have the radio security code handy- you will need enter it to turn the radio back on.
Al

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