'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

__________________
A Dalton

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

ign

__________________
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

__________________
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.

__________________
95 E320 Cabriolet, 169K

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.

__________________
A Dalton

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

http://catalog.worldpac.com/mercedesshop/sophio/image.jsp?title=Water%20Temp.%20Sensor&url=http%3A//img.eautopartscatalog.com/live/C602012373FEB.JPG

In the water jacket ..I think in the head on that chassis..you will find it

Continuous Injection System

The sensor is 2 thermistors in one case , so they have to read the same , regardless of temp... the ohm reading is taken diag across the pins for each sensor..

__________________
A Dalton

When you say "button" what exactly do you mean and where would I be looking for these "blinks"?

Model/Year needed for that info.

__________________
A Dalton

1991 300E 3.0 liter