'92 300E (California car) with 136K mi. - My CEL has been on for the past four days. The car seems to be running normally. The first time it came on, it stayed on for a while even after shutting off the engine and removing the key. After that one time, it turns off when the ignition is switched off. How do I retrieve the fault code? Is the LED supposed to be blinking at the terminal block back by the battery when the ign. or engine is switched on? I'm seeing nothing. Also, is there a list of the fault codes somewhere?

Thanks for any help.

Press the button and hold it in for 3 secs, release..then the codes will flash back..count them

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A Dalton

Thanks Arthur. Is this done with the engine on or just the ign. on?

ign

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A Dalton

Well, when I got home I turned the ignition on, held down the button for 3+ seconds and all that happened was that the red LED came on as soon as I pressed the button and went out when I let off the button - no flashing at all, during or after the button press. Could this just be a fluke? Is there a way I can clear the CEL light and see if it stays off or comes on again?

Try 2 sec ..if there is a CE lamp, there is a code

Use the search feature..it will tell you all about code retrieving

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A Dalton

2 sec. did the trick! Code 17 - any idea what that is or where to find the info?

http://www.geocities.com/MotorCity/Downs/1039/mercedes/cs1000_mb.pdf

Use the Archieves , Man ..it is all in there for ya......
Look like a shorted/open 02 sensor.

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A Dalton

Thanks a lot for your help Arthur. I've been trying to search for the answer, but there's an awful lot of stuff to wade through that really doesn't apply (at least in the searches I've been doing)

If I'm reading it right, code 17 indicates a bad 02 sensor. I happen to have a good used one on hand so I'll try to swap it out this weekend.

Should the CEL light go out on it's own, or do I need to clear it once I've replaced the sensor?

If you did a search, you would have seen how to clear the codes...

but, here you go.
After the code retrieve, wait 2 secs,. hold button for 8/9 secs , turn ign OFF for 10 secs ., ON for 10 secs , start car..code will be clear and CE will be out.

Did you try for any other codes ???

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A Dalton

Phalcon, here's a start... http://www.peachparts.com/shopforum/showthread.php?t=107630

Somewhere among the thread and its links you'll find what you need.

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95 E320 Cabriolet, 159K

It appears that there are 2 codes;17 (O2 sensor is shorted to pos. or gnd) and 29 (CFI and Ign. Control module reading different engine coolant temps). The O2 sensor I can replace with a good used one I have, but I'm not sure what to do about the other code. Any ideas? Are there different temp sensors associated with different electronic modules? Is there a way to test them?

Thanks Kestas.

I would change the 02 sensor...and I would unplug the 4 prong CIS sensor and clean the pins and plug it back in, clear the codes and give it a run.
If that code comes up again , then you have to ohm that sensor and see if both sides read the same [ it is 2 sensors in one] ..if not, it has to be changed ..but b/c they are thermistor sensors , a poor connection at the plug will read as a ohm value difference at the ECU , so try that first.
That other post gives the same site as the one I gave you earlier and those codes are HFM/SFI and are not for your car. You have the coerrect codes now.. as far as having all the codes , you know that when you do the retrieve procedure and it finally starts to repeat the first code you got..you then know it has gone thru the entire code search sequence.

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A Dalton

Please excuse my ignorance, but what does CIS stand for and where do I find this sensor?