First off, I am new to the forums and have been driving BMW'S for the last 6 years or so, and just purchased my first Merc! I got a great deal on a 2008 C300 fully loaded with 37K on it. I love the car so far and have been reading (trolling) the forums for about a week now and have everyone seems pretty friendly here!

First off I dont like really posting with a issue but I think about 95% of the members here seem to post with an issue they are having.

I have been searching this forum on this before so I am pretty sure I might already know the answer to this but maybe someone with more knowledge will help some. I got a CEL which has not turned off so I turned on the OBDII and it flagged the P0170 Fuel Trim (Bank1) error. Now it ONLY flags that error code not any OTHER codes. I have read when it flags that code and the P0173 it normally is the MAF sensor on the car. So really my question is if it just flags the P0170 is that something else? There doesnt seem to be any problems with the car at all it drives just fine. I think the dealer did a OIL change before hand and may have messed with the AIR FILTER, but not sure on that.

I have NOT pulled the AIR FILTER out to see if it was seated correctly in the box, only thing is that someone might have put wrong gas in the car but I dont think that would be the cause, I have reset the light but it came on in about 20 miles again. So I know it is reading something. I was just seeing if anyone has some insight on maybe I just just pull the MAF and clean it then go reset the code and see if that fixes it, again the car has 37K on it. I guess also if the car is running just fine is also a CAUSE of concern (high importance fix) or just something that needs to be taken care of as soon as you get to it. Thanks!

 

Take the airbox completely off and re-seat everything, see if that fixes it.

 

I am going to give that a try tonight or tomorrow. I guess the main thing is the filters needs to make sure they dont have a lip on them and they are in the box good?

 

Just make sure the filters are flush, and the air box is seated properly and the air pump hose is properly connected (arrows pinting to each other) If you are unfamiliar how to remove the assembly, it is quite simple and can be found here:

https://mbworld.org/forums/4059025-post31.html

 

And be sure to reset it again after you do so to see if the problem persists

 

Thanks I just took it apart, The airfilters were sealed good it seemed to be but i took them out and found some Pecans, interesting!

Now I conencted all hoses back and made sure everything is seal tight to my abaility, now you said something about the AIR PUMP hose by chance are you talking about one of the hoses that I disocnnected when remove the cover? If so then I made sure those were sealed back good or is by the MAF?

Also I cant reset until tomorrow since I got to get the OBD tool again, I guess that doesnt matter if I drive it before the reset does it?

Thanks?

 

Yes one of the hoses that you took off (the one with the arrows that point to each other) just reset it tomm and see how it goes. If it fixes it, make me a pecan pie lol

 

LOL, I think there might be squirrels in the engine! For the hell of it I took out for a test drive to see how it drove, the light was still on of course but maybe im smoking crack here but it felt really more responsive on the throttle than before. I will get a reset on it in the morning and see how it goes. Thanks for the replys

 

Yea reset it, it usually you have to drive X amount of miles for it to reset on its own

 

Well it looks like the light came back on. I notice that the LIGHT only will come on if the car is "IDLE" like I said I dont really notice anything different.

If it is MAF should maybe I just try to CLEAN it first and see, could it be possible that GAS could have caused this?

Thanks

 

Gas wouldnt cause that, you can try cleaning the maf

 

I cleaned the MAF and so far there has been no light, so maybe that was the fix, if not i got a extended Warranty on the car I will jsut get it replaced. Thanks!

 

Good to hear

 

Well wanted to give an update, about a day or so after the MAF was cleaned the light came back so I just got it back from the dealer.

The tech looked at it and said that "Air Box was not proper;y secured to the air mass meter" So he resecured it and cleared teh DTC's and the mixture adaptations.

Now, what I dont understand is I purchased the car from a non MB dealer and the lght came on after about 400 miles when I bought the car so the dealer must have misplaced it on the AIR MASS METER and apperently I misplaced it twice, not sure how that is even possible since it only goes on there one way it seems, so i guess ill wait a few days and see if the light really comes on, now im little nervous about doing my own air filter change if that damn light will come on.