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McLoffs 08-02-2003 02:31 AM

W124 check engine light/pulling codes
Hello. Tonight the check engine light came on on my 1993 300E. I searched around a bit in the ShopForum, and think I figured out how to pull the codes. I fired up the engine, pushed the button, and the LED flashed once. No fault.

Am I pulling the code the proper way? And if so, what else should I do to figure out what's causing the light to come on?


Arthur Dalton 08-02-2003 10:54 AM

Turn key ON

Hold button [ led will light when holding ] for 2-3 secs - release

The first stored Code will flash back -write it down

Do above sequence after each code flash until the codes [ if there are more than 1 stored] have returned to the first code ... They will come in numerical sequence .. 3,5,7,8,etc.......

You have to have at least one code stored or the CE would
not be on....

McLoffs 08-02-2003 04:50 PM

I did exactly that, and got no flashes -- the LED lit up as I was holding it down, and after I let it go, nothing happened. Any ideas?


Arthur Dalton 08-02-2003 06:28 PM

Is the CE on???

McLoffs 08-02-2003 07:26 PM

Yes, the light is still on.

Arthur Dalton 08-02-2003 07:31 PM

Retry the led/sw , holding for both 2-3 and 3-4 secs. with key in the on position...

There should be a code stored or you would not have a CE .. unless you are having a wire harness issue ???

The led is lighting when you hold the button, correct???

McLoffs 08-02-2003 07:41 PM

OK, I just went out to the car again. Key in on position. I pushed the LED (which lights up when I push it) for 2-3 seconds, 3-4 seconds, 5-6 seconds. I noticed something else I hadn't before -- after letting go of the button, there's a very faint flash of the LED (just once).

I also noticed there was a clip loose on the part that connects the air box to the tube that goes across toward the back of the engine. Could this have been causing the problem? The light is still on; don't know if it stays on until reset, however.

Thanks again,

Arthur Dalton 08-02-2003 07:46 PM


Try this

press led 2-3 sec . if any flash comes back , wait 2 secs and then hold the button down for 8-9 sec.
[also do this if NO flash came back]
Now turn the key OFF for 50 sec , turn key ON for 10 secs, and then start engine
See if CE goes out

McLoffs 08-02-2003 08:02 PM

I did exactly what you, and the check engine light is still on.

Any more ideas?


Arthur Dalton 08-02-2003 08:15 PM

Check along the wire harness for insulation degeneration...

McLoffs 08-02-2003 08:40 PM

There were a couple places in the engine compartment where the plastic around a bunch of wires had come loose. Would this be enough to make the light come on?

Also, should I be worried about driving the car?

Arthur Dalton 08-02-2003 08:42 PM

do a search on Wire Harness..

McLoffs 08-02-2003 09:25 PM

I did a search for wiring harness, and read about the problem that can affect my car. However, in digging around the wiring in the engine compartment, it's the stuff that goes around a bunch of wires that's crumbling, not the insulation for individual wires.

kidMoBile 08-02-2003 11:44 PM

Okay, I'm not trying to be a wise ass or anything, but I'll relate a somewhat embarassing story to you. I had a light go on on my dash a few months ago (two weeks after purchasing), it looked like a cross-section of an engine with an exclamation point in the middle. This is exactly what a check engine light looks like on every GM product that I have ever owned. I hunted for codes with the push button LED diagnostic center and got nothing. Of cours it turns out that this symbol meant that I had an exterior bulb burned out (GM would never think of warning the driver of this), and only then did I realize that the check engine light on MB actually says "check engine". I only mention this because you said it came on "tonight", and the exterior bulb warning light only comes on when the headlight switch is switched on. My apologies if this post is obvious; just hoping that I'm not alone in being the most ignorant member on the board (ignorance loves company!)!! Good luck!

McLoffs 08-03-2003 06:12 AM

I've had the dead bulb light come on a number of times (one of my rear side-marker lights comes loose sometimes) so I'm entirely too familiar with what it looks like. :-) Unfortunately, this is the check engine light. In true M-B fashion, it says it right on it. Hopefully I'll be able to figure out what causes it to come on.


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