Check engine lite comes on frequently. I have been shutting it off for some period of time by taking the neg terminal of the battery off for a time. I have been reading about the code reader under the hood on the right side. Most people talk about a 16 pin connector. Mine has an 8 connector plus an
LED and button. With the key on, If I hold the button for 4 seconds the LED is on, when I release the button the LED doesn't blink at all, even though the Check Engine Light is on! I have changed the 02 sensor. Can someone please shed some light on this 8 pin connector, and how to clear fault codes with it?
Many Thanks,
Bill

 

I have the same problem as you but I just take out the negative terminal as well.

I did it a couple days ago and it hasn't come back on since. It's nothing my mechanic has noticed either.

 

It should blink a few seconds (maybe as long as 10) after you release the button. If not, I would hold it down for another 4 seconds.

 

OK, I got the blinking light to work on my 94 E420 and it blinked 8 times. Can anyone tell me what this code means and how do I permanently clear it?
Many Thanks,
Bill

 

http://www.mercedesshop.com/shopforu....php3?t=107630

It should have more than one to check, not to assume that every code is exactly the fix, it takes time to troubleshoot. I've replaced everything a code once told me and it wasn't the problem at all, sometimes it can be an oxygen sensor or vacuum pressure, or just about anything...

Use it as a guide to start your troubleshooting. After an engine rebuild, it was gone for over month, but it came back, and my mechanic still can't find it either.

Good Luck!

 

can someone post of a pic of where exactly on the right side i should look for the LED and button to diagnose a check engine light? I looked around under the passenger side hood near the battery of my '93 300CE but didn't see anything similar... I think it was just the OVP and something else (no LED tho)...

 

I thought it was only on the 94-95's? But I could be wrong..

 

I've seen posts from members with pre-'93 w124s reading fault codes but not clear if its via home-made code reader or through a built-in system... Also, have read some posts referring to reading codes from somewhere on the driver's side under the hood vs. passenger side. In any case, some pics of exactly where to look would be helpful..

 

end of 94 is when they stopped. ( I think) but on a 420 its located on (if looking at the engine) the top left corner of the engine compartment.

 

hmm, description of exactly where? I looked around but didn't see anything that could resemble an LED + button setup in the passenger side engine compartment. Thanks

 

sorry cant post a picture right now, but it should be by your 38 pin connector. it'll have a cap over the top of it so its not visible to the eye you just got to look around.. you'll know when you find it! you'll see white numbers either 1- 8 or 1 - 16 i'm not sure for a 300ce and the led light!

 

Sounds like a CEL epidemic!! Mine does the same thing! Take off bat cable and will stay off for quite awhile! I am thinking O2 sensor but not sure yet!!


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