Please help.. OBD codes P0171, P0172, P0175
 

Hello everyone,

I drive a 2009 C 230 (W204). One month ago I got a check engine light on and I found OBD codes P0171,P0172 and P0175(not at the same time. keep changing every time after I reset the CEL). So I replaced both Engine air filters and MAF sensor(both from Mercedes) and erased the code. But it came back after about 40 miles of drive but later I found out from one of the old thread that I have to wait around 100 miles for the self adaption to happen after the replacement of MAF for the ECU to write down the new values so I have waited and one fine day the CEL automatically disappeared and I was happy. Unfortunately 2 days ago, the CEL came back again and when I checked for the code I found P0171 was returned. I didn't erase the code this time. I don't know what to do. Do I still need to wait for self adaptation or any other component is faulty? On my inspection I didnt find any vaccum leaks. I have a system live data recorded using my OBD code reader. Can anyone tell me what to look on it?

Thank you,
Hiran.

If you have a live data reader, then you should look into what each bank is throwing for information. 171 pretty much means that you could be running too lean.

So for starters see what each bank is throwing out for numbers, if one is not like the other then you can go from there.

Another thing you can do is run the car for about 10 minutes, pop your hood open, turn off the car, and check for any "hissing" sounds when the engine turns off. You could have a cracked seal or something like that.

I will definitely look for that. By the way I am trying to upload the live data

I managed to upload the live data..anyone please tell me what to check on this? Thanks

That is odd. One lean code and two rich codes. With that P0171 I would check vacuum.

Hi. Anyone please explain me what does this values mean?
STFT B1: 14.1 %
STFT B2: 14.8 %
LTFT B1:4.7 %
LTFT B2: 3.1 %

Hi..Thank you for your reply.Since there are 2 lean codes on both banks,I believe O2 sensor is ok. Later I got the freeze frame data
STFT B1:14.1%
STFT B2:14.8%
LTFT B1: 4.7%
LTFT B2: 3.1%
Since STFT B1 & B2 are above 10%, I decided to take it to the mechanic today but in the morning when I started the car,there was no CEL. So do you think is it an intermittent fault? So now less chance for vacuum leak?

Update: Today I got my car checked with a local garage and pulled the code
P2004 with their equipment. It's saying tumble flap intake manifold short circuit to ground of sensor lines/tumble flap shafts stuck in actuated position. Any
Thoughts? A temperature sensor change will work?

What engine is in the car (i.e. what model - C250/300/350)?

It's 2009 C230

OK, P2004 is definitely a problem with a tumble flap inside the intake manifold. If this error persists, the manifold need to be replaced before something breaks loose and enters the combustion chamber and causes real damage to the engine. This would not be causing
the other errors.

The other errors you posted are all generic OBDII codes. Each one of those actually relates to three different MBZ-specific DTCs (here's the DTC list for your engine so you can search them: http://benzbits.com/DTC/DTC%20209.372.pdf

Looking at SDS, the one thing all of these have in common, is they say to check the pressure sensor, part reference B28:

https://cimg4.ibsrv.net/gimg/www.mbw...68ec34ac0c.jpg

Thanks Mr. Rodney. I have few questions regarding the intake manifold tumble flap. First of all, will it give an intermittent CEL if this tumble valve broken? It's like every hundred kms approximately CEL comes on and off(happened twice)
2)can I fix this problem by using a special intake manifold repair kit found online or I must replace with new one? Any idea about the reliability of the repair kit?
3) what do you mean about the pressure sensor? Can I try replacing it or check the voltage?

See replies to your PM's. Listen to Rodney regarding inlet manifold on M272 engines!

Thank you all for the great help. I will possibly get my intake manifold changed by next week. One more thing I wanted to ask here is that I have read some threads about the reliability issue of M272 engines and is that a wise decision to keep this car even after repair? Any suggestion is highly appreciated. Thanks

You are stuck in the actuated position because the plastic on lever connected to the actuator broke. Fix it with an actuator/lever kit instead of getting a manifold. Grab some additional vacuum hose because the hose at the MAP sensor tends to get aggravated when you do the repair. The 272 is a very predictable and reliable engine, google can be scary but the engine and the car are phenomenal.


--Kyle

Did you ever get the P0171 code cleared?, What was the root cause?
I have 2010 C300 and having the same issue and interested to know how to resolve this. Thanks

Hi Matt

I had to change my intake manifold and also replaced all 6 spark plugs. Intake manifold costs me 600$ (From MB)and the labor including the spark plugs cost me 300$(Bosch). By the way I am located in the Middle East so the costs vary from your place. My misdiagnosis was the Mass air flow sensor.

Oh wow that is quite a high cost to repair. How can code P0171 change to P2004?. Was it done using different reader? My 2010 W204 so far only have P0171 and P0174 which I am hoping really just that MAF and not the intake manifold or anything costly. I am really trying to avoid coming to dealer as they are a rip off.

Codes can't "change". Must have been a different condition present when the original poster had it checked a second time.

Generally, P0171 and P0174 relate to a vacuum leak. Seeing as it affects both banks start by checking for leaks before the intake. If your MAF is bad you would have an additional code for that.

Calling dealers a ripoff seems kind of strong. People have negative and positive experiences with dealers and you can debate the merits of what they might charge compared to indy shops, but if they would be in the business to rip people off they wouldn't be in business very long. Just my two cents, and, no, I do not work for a dealer.

Hi..Matt
yes..that was done with a different reader. Only that time I realized my reader(Innova3130 c-very dissappointing) can't read manufacturer specific codes so I found the other code from a local garage. And replacing MAF was neither cheap coz it cost me 330$. and obviously that was before I go for manifold. and what I know from many of my research in the internet that the modern MAF sensors doesn't go bad like before so my suggestion is to check for vacuum leak before you go for any part replacement

Hi Hiran,
Took the car to local service that specialized with Mercedes (Not dealer) and did smoke test and found I have the same issue like yours that is leak on the intake manifold. I have to change the whole intake manifold and its a very expensive service. I am very shock with the cost. The place I went to always carry stock at hand (since it is common issue).

Hi Matt,
Sorry to hear that. If it's only a leak from the gasket, why you have to change the whole manifold? You can change the gasket instead? In my case they said the valve inside is broken(I couldn't c). So you can check before you replace. I think it's ok to run few miles like this.