Hi, I am new to this forum and from what I have seen this is great.
My turn to pick your brains, if you don't mind.
I have a 1998 C-280 Sport, with 57,000 miles, which I have recently purchased second hand. Brought it in to a local independent shop for a "check engine" light.
The problem keeps coming back. The codes are "170' and "173", also with a note about a problem on the left bank. Not too sure what the tech told me.

Can one of you top dogs help with suggestions of what the problem could be? (I'm afraid the shop doesn't really know what the problem is)

Thanks in advance for your help, appreciate it greatly.

Andre

I'll be the first one to tell you I am not a top dog but you need to have the DTC's checked before anyone can tell you what is wrong.

The codes are probably PO170 and PO173. I think these may be misfire codes, but am not sure. If the engine runs OK, and I am correct about what the codes mean, it may need a control module. I think the PO170 is a misfire TWC damaging, a "general" misfire code, and the PO173 refers to cyl 3 misfiring. There were some problems with the early 112 engines running too lean on start-up, it will act really doggy when first started. You'll get these misfire related codes when it does this. I'd have a dealer check it out, they may be able to cover it for you.
If the tech said something about self-adaptation being at limit at part-load, then the code may be pertaining to the mixture self-adaptation, or "block-learn" in generic nomenclature, being as far either rich or lean as it can go. The problem then is usually the mass air flow sensor.
If no one else has any ideas, I'll try to post a more positive answer on friday night.
Gilly

What the codes mean is that the engine is running to the computer lean/ rich stop. ALMOST all of the time this is caused by a bad air-mass sensor!! Part number 112-094-00-48, list is $274. Most of the 1996 & later U.S. cars have a 8yr/80,000 mile emission warranty!! POSSIBLY this sensor COULD be covered under warranty!!!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thank you
Stan Pittman
gillybenztech
M.B.DOC
for the information.
The technician was scaring me telling me that the code meant that the engine was excessively worn which didn't give me confidence in the guy, as the car ran perfectly despite the codes.

He did say he wanted to replace the mass air flow sensor and go from there

I told him that I had gone in a web chat room and it seemed that the air sensor sounded ok. I also told him that someone had eluded to PO173 referring to the cyl 3 misfiring so I asked if this could be the problem. He said that the computer would tell him exactly that and it wasn't the case.
He thought it was a vacuum leak on the left bank (I hope his pride isn't getting in the way, it's just that the car has been in the shop since Monday and I'm getting a little tired)
He seems to be honest on the parts. He was telling me the sensor was $300 but who knows what the labor will be.

Can someone give me more details on PO173 and to what it is all about (what specific parts).

Ah yes! I also have a HI oil light that comes on
and he says that it is a bad sensor on the motor
as the oil level is between the hi and low mark on the dip stick
He was replacing that and the air sensor today.
Too bad M.B DOC's message hadn't come in earlier.

That's life I guess
Thanks again for the help

Andre

P0 173 has nothing to to with misfire!! Again just like the P0 170 code this is reletive to engine mixture being too lean. ALL misfire codes are like P0 300, & that is for random misfire. Also P0 301, P0 302 & so-on depending on the number of cylinders. The air-mass sensor shoulf elimate both codes that were present.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thank you M.B.DOC
then I guess the tech is on the money with what he is telling me
You are restoring my confidence in him.
His problem is that he is not fast with repairs.
It is just that in the 3 weeks that I have the car 2 of them have been in the shop
First week he change steering damper, centerlink assembly, tie rod, and bushing

Now he will also change the universal joint between the steering wheel and gear box.
It has play that you can feel on the steering , the part should be in today
Rear shock are also finished. I will change them myself, over the weekend. I got them from Thepartsbin ,cool place.

This 280 is in Florida. The roads here are nice and flat, is this normal wear on a Benz of 57K ?


and now the check engine light I am starting to wonder if I can afford this for long, hope this Benz is not a money pit

again a must thank you for your help it is greatly appreciated

Andre

Andre:
I would say that wear on one of these front end components may be typical of almost 60,000 miles of use, probably hard use would explain it better, like lots of pothole city driving, or very aggresive driving. It is unusual that the mechanic is finding unacceptable wear on so many components. The link between the steering gear box and lower steering column shaft I would consider very unusual.
If at all possible, see if you can change the mass air flow sensor yourself, it is a very easy job. BUT the check engine light will need to be reset, ie "turned off", it won't go out by itself.
I checked on the codes, it is as MB DOC explained, the self-adaptation is at the limits, and the mass airflow sensor is the usual problem, happens alot with all manufacturers, not just MB.
The PO170 is for the right bank of cylinders, the PO173 is for the left bank. Sorry about the confusion with mentioning misfire codes, I believe MB DOC is correct with mentioning PO300 codes are misfire codes, then there are codes such as PO301 indicating #1 cylinder and so on.
I would also follow up on the advice concerning trying to get MB to cover the cost under warranty for the check engine light, it should be covered whether you are the original owner or not.....
Happy Moteren
Gilly

Download this: Pages 134 to 149 list the fault codes. The whole manual makes for interesting reading.
http://www.autolib.diakom.ru:8000/CARS2/pribor/cs1000/manual/cs1000_mb.pdf