Ok, here I am with another simple question: Where is the ODBII plug on my 1998 C280 (202.029) located?

On my 2000 C 230 K, it is about 18" ahead of your right knee, when you sit in the driver's seat.
A little " trap door " you pull down.

__________________
2007 C 230 Sport.

Thanks so much! I took it by AutoZone and found that I have the following error code:

P0137- Fuel Trim Malfunction - Bank 2

Not sure what that means yet. Any ideas guys?


NOTE: After doing many searches here, I have come to the conclusion that the guy at AZ may have transposed the error code when he gave it to me. I think it may be P0173??

Did a search on fuel trim malfunction quite bit of info came up might oughta try it. Checked your gas cap to see if it is on properly? Info talked about the gas cap seal among other things.





Jim

Yes, I checked the fuel cap and gasket the first thing! I have found a few possibilities.

This morning, the light went away! Now that dumbfounded me, because no one had mentioned that theirs went out by itself for this error.

I am going back to AZ today (a different one!) and have it rechecked, just for the "warm fuzzies". Then I will proceed further.

Thanks for all the help, guys! It makes me feel good to have so many MB owners out there who are so helpful and wise!

P0173 is a fuel adaptation code which has nothing to do with the gas cap. A gas cap code would be P0455: large leak in evap system or P0442 small leak in evap system.

An adaptation code can only be evaluated by reading the adaptation numbers. The code will probably still be there unless the battery has been disconnected. The lights shouldn't go out but they do. It should take 40 key cycles with no fault to reset the light but some continuously monitored values will come and go but the code stays there in any case, till erased by scanner or battery removal.

A P0173 code will only apply to one bank so the numbers are especially important. There are two sets of numbers that will set the light. These are the partial load multiplicative adaptation numbers and the CTP (closed throttle position) additive adaptation numbers. One of the numbers will be at the limit or real close. Knowing which will be the mechanism for diagnosis. I wrote a little about this in an article that appeared in last months "Import Car" a trade publication:

http://www.babcox.com/editorial/ic/ic60442.htm

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

A PS on the last reply, when "Import Car" places articles into their archives they reduce the pictures to about a useless size. We have started redoing articles I have writen in our own site using original pictures. This one was in last months issue and we haven't had a chance to redo the pictures. There is a test toy we built for this article that some might find interesting. It the pictures and description aren't legible I can pull up better views.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Very nice article, however, since I am not a MB certified mechanic, it didn't translate to anything I understand about my situation. WAY over my tiny head! This is my first MB to ever own and I am struggling to understand all its nuances of operation. You'll have to "dumb it down" for me. (after all, I am a result of Gdub's educational system here in Texas. We ain't got no learnins!)

Thanks for all your input. I am going to study up and see if I can understand this issue.

cl

OK, dumber you get: you need an Air Mass Meter..... or something else.


That's the Michael Moore approach.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

That seems to be the approach of many others dealing with this particular CEL. Will pull out my CD manuals and schematics and track it down. Meanwhile, I am off to AZ to doublecheck those CEL numbers!

Thanks so much!

I had a DIFFERENT AZ check it again and it definitely is:

P0173- Fuel Trim Malfunction - Bank 2

So far, I have found NOTHING in the archives on this one for a 98 C280.

Just what is it that you expect to find. There are reams of pages on the P0173 codes and all the v6s are basically the same: C280, E320, ML320. The v8s also have the same situation in E430, ML430, etc.

If you aren't able to understand the concepts involved, what else would you like. Are you doing your diagnostics using the Blue car method? The blue car method states that the last time a blue car acted like that it was an AMM. I gave it to you both ways, but I suppose the Blue car method is really based on a statistical approach, so one answer isn't enough. Now that I have expanded the description of the Blue car (e320 Ml320 etc) you should be able to find the statistical answer to the Blue car technique.

Using anything but the Blue car approach will require understanding the concepts involved and finding access to the tooling required to accomplish the testing required. The only reason I point all this out is that using AZ as your info and tooling source you are stuck using the blue car technique.

The article was writen for professionals and many on these pages will figure out the concepts, there are some really great DIYers here. If you wish to use the blue car approach for fun you will find it an expensive hobby.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

stevebfl,

As I have stated before, I am a rookie to MBs. I did not know ANYTHING about any commonalities within the many models of MGs. No, I do not megadollars of special test equipment for MBs either. (I HAVE ordered an ODBII interface for one of my laptops and the software, however) I do have a background in electronics and computer science, just nothing automotive.

I didn't realize that everyone here are professional MB owners/technicians. I appreciate all of your attempts to educate me. Generally, when it comes to automotive repair, the "blue car method", as you call it, along with small amounts of advice and good historical information usually works for me for most other types of cars, motorcycles and planes.

Again, my apologies to everyone for wasting so much of their time and bandwidth. I have found most of the people here to be very helpful and tolerable of my incredible lack of MB knowledge.

cl

stevebfl, I hope you're still subscribed. I loved the article you linked above--it's over my head as well, but I've been dealing with a CEL problem for a few months, so most of the codes and jargon are becoming familiar. I just tried my third "new" AMM (I say "new" meaning "new to me"). The first one was the wrong model, but my independant mechanic had it on his bench (from a ML320) and suggested I give it a try. I successfully drove to a very nearby office park, where I floored it and it quickly went into limp mode. We put the old one back in. Fine. Then I ordered one from ebay, put it in at home, quicly went someplace I could floor it: limp mode again. At this time I figured that I had tried a wrong AMM and a bad AMM, and that maybe mine wasn't the problem at all (OBSII codes were P0170 and P0173, of course). But after months of driving with CEL on, I tried another AMM from ebay (different seller, one with lots of AMM's). This time I read the codes after replacing the AMM, and several P030x misfire codes in addition to the fuel bank malf's. I reset the light, and took it for a slow, easy test drive; no floring it immediately this time. After gradually bringing it up to highway speed, I did some spirited passing and, lo and behold, no CEL, no limp mode. This would appear to be consistant with what you said on page 3 of your article, that when the 1.32 adaptation falls to 1.0, random misfire codes ensue (I got five: P0300-P0304B). My questions (finally; sorry for the long post), is it possible that I was too quick to stomp on the earlier AMM replacements, and that had I been gentler, they may have worked? Am I even wise to believe that this AMM has solved my problem? And am I correct when I infer that the whole time my CEL has been on, I've been burning 15-32% more fuel than I'm supposed to? Thanks for the article!

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2002 C230 Coupe + 2003 C320 4Matic Sport
http://img.photobucket.com/albums/v1.../sigpic5-2.jpg

CL:
What Steve is trying to say is kind of like when Ike and Tina Turner did "Rollin' on the River": "We can do this easy , or we can do it rough .....

I think what he is implying that it would be better to do a proper diagnosis, with about 90% probability the problem is the Mass Airflow Sensor. The "90% probabilty" is where the "blue car approach" comes into play. A more detailed description od the "blue car approach" to diagnosing is: "The last blue car that came in here needed a Mass Airflow Sensor, therefor ALL Blue cars need a Mass Airflow Sensor:, which is BS of course, but the bad Mass Airflow Sensor on these M112 motor cars is very common. Don't get too hung up on the fact that your car is a C280, because these are OBD2 cars, the code numbers and fault description are the same not only between other OBD2 cars/trucks made by Mercedes, but in fact all OBD2 compliant cars in the US!

To do a proper diagnosis you'd need a scan tool (not just a code reader like AZ has) to look at the fuel trim numbers.

Gilly

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