I have recently acquired a '96 C280 from my brother in law. I am taking the responsibilty of smogging the vehicle for the name change (being that he is family) problem is recently the battery was disconnected and I have since found out that the "codes" have been "cleared" and now the car will not smog because it is not getting a full "reading".
I hope this makes sense.....
Anyway, the smog guy keeps telling me to drive it some more, I have gone back about 3 times after putting 100 to 200 miles (each time)and it still is not getting the full reading to pass the smog.
What the heck is going on? Did unhooking the battery clear all the memory in the "brain" of the car or something. I don't know how I am going to get this thing smogged.
Any suggestions?

THANX!

 

I am in the same situation... purchased a C240 from a family member and am trying to get it smogged. It passed the emissions portion but did not complete the "self check" so it failed smog. I also was told to drive it so it would clear the codes. The engine light is not on (it does cycle on and then offnormally during startup). I have spoken w/several mercedes repair shops and they have told me to bring it in ($90 to diagnose). They will hook it up to a computer and, if nothing else is wrong, clear the sensors or codes that have been triggered. I hope to take the car in in a few days but what a hassel. I have a generic OBD code reader but it apparently doesn't read the MB codes. I don't know if there is a diy fix for this. I am wondering how to avoid this situation everytime you disconnect the battery or what sets these codes off and is there a way to read/clear them yourself?

 

Weird hah?
Well, not being completely familiar with MB's it really leaves me in a unexpected position because obviously the battery would have never been disconnected had I known this would happen and completely screw up my smogging situation.
So...... I guess it looks like I will have to invest $$$ just to find out what the "problem" is.

Thanks for your input.

 

Hey - I'm having the same insane problem -- how did you work this out!?

 

ECU /engine management system/ is of the 'self-learning' type which means as it operates, it adapts to changes in operating conditions, and store the optimum settings found.
When the BATTERY IS DISCONNECTED, these 'learned' settings are lost, and the ECU reverts to the base factory settings. In this case, when the engine is restarted, it may idle and run roughly until the ECU has 're-learned' the best settings. Take the car for a road test of at least 15 minutes duration, covering as many engine speeds and loads as possible, and concentrating on the 2000 to 4000 rpm range. After that, let the engine idle for at least 10 minutes, turning the steering wheel occasionaly and switching on high current draw equipment such as the heater fan or heated rear window. Also, windows and sunroof positions must be re-programmed by holding each operating switch for a few seconds. Overall, ECU system need power at all times. Otherwise you think that something is wrong with your car, but it is not. Your car is OK. Next time clear the codes with scanner.