My check engine light went on. I read the code and got only a Code 3 (Lambda control inoperative). The car runs fine. Where do I start looking for the problem?

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95 E320 Cabriolet, 159K

Erase it and see if it comes back, if so, replace the oxygen sensor.

See what it is coupled up with at pin *8

Arthur, how do I perform this procedure?

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95 E320 Cabriolet, 159K

with an LED code tester...you can build your own:

http://members.aol.com/ajdalton7/ledtool.jpg
also check out this thread: E320 16 PIN DTC Charts inc. pin 8, pin 14

or buy one from me...see my ebay link

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

Hey
Do I get Royalties ???????????????????????????????

Just make the tool and then you can get the codes from the other modules .
R Shack parts .. $5 will do it.
Getting the codes is the same as the built in sw/led you used for the diagnostics module. Interpretation is the key.. post what you find.

Haha If i gave you royalties then wouldn't I have to pay out to every other member who posted code descriptions, model information, connector locations, etc.

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

I think you over-priced it a bit....
I had made quite a few for members and tech friends over the years , and some are still being used...but I never sold any.
Doubt you will get $50 for one, though you never know . if one can get $30 for a 19 cent resistor for aux fan, guess one can get $50 for a 49 cent diode..
good luck to ya .. I like the spirit of it ..
Want a simple OBD11 other one to try ??

Okay, back to me now. I made the code reader and got a Pin 8 Code 13 (O2S [Lambda] control system operating at rich or lean limit). What's the next step?

For the heck of it I checked Pin 14 and got Codes 2,5,11. Anything to worry there?

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95 E320 Cabriolet, 159K

if you look at the thread that I posted you'll find this:

PIN 14
code 2 = EA/CC/ISC control module (N4/1) or Safety contact switch (M16/1s1) or Stop lamp
switch or Cruise control switch or Actual value potentiometer or Starter lock-out/back-up
lamp switch or engine speed signal or vehicle speed signal or closed throttle position
switch or safety relay in EA/CC/ISC control module
code 5 = Stop lamp switch (S9/1)
code 11 = Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI)
Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)

Before replacing anything I would reset the codes and then see what returns.

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

Yes, I checked your link for Pin 14 codes and copied them for my personal archive. I imagine the codes are nothing to worry about.

Anyhow, I cleard the codes - though for some reason I couldn't clear codes from the built-in code reader - and the check engine light is now gone. Did the car just have a hiccup, or should I still check something? I did a search and found a post where somebody mentioned that O2 sensors seem to need replacing around every 60K. My car has 67K.

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95 E320 Cabriolet, 159K

I would drive the car a few days and then check the diagnostics again. If the same codes show up then you know there's a problem there.

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Daily Driver: 02 E430 4MATIC
In the family: '03 E500 // '04 ML500 // 64 220SE

Quick and stupid question while you guys are on this topic-- where's the on-board code reader? 95 e320 for me, too.

It's in front of the battery mounted on the inner firewall. Flip open the lid, press the button for 2-4 seconds (ignition switch at ON position), and you're reading codes.

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95 E320 Cabriolet, 159K