Recurring check engine light on C200k, no obvious faults, pls help!

[Silverspa]

Hi all,
I'm a newbie so please be nice! I would be sooo grateful for your
help as my MB garage seems to be clueless!

I bought a used C200K Evo in December 2008 from a private dealer. 2
days later the check engine light came on, so I took it to MB dealer
who produced the following code:

P200B-004 B2/5 (Hot film mass air flow sensor), Plausibility error
Mass air flow sensor / Throttle valve [P0101]

I took it back to the dealer who (after considerable arguing) had
his mechanic replace the mass airflow sensor, and the light went
out. A couple of weeks later I filled the car up with petrol at
Sainsburys and when I switched on the car, the light came back on.
Took it back to MB who said there was no fault and it could be a
faulty sensor, but charged me £50 to cancel light, and apparrently
not much else. Next time I filled the car up light came back on.
Took it back last Friday and they cannot find an obvious fault
(didn't give me the DAS printout this time, I will ask for it),
switched off light and it came back on today after driving round the
block for 10 minutes (1 day later).

I've read all the posts and Googles, reading probs from dirty
throttles, leaking oil, dirty cams and bad engine harness wiring. My
engine looks spotless and I can see no leaks.

If you know what might be wrong (and how much it will cost me to
fix!), please let me know!!

 

[BlackC55]

This engine sufferes with this fault and it can be caused by a number of issues. The air mass fault code is a red herring and it just means that there is an amount of air entering the engine out of spec of what it should be so throws up and air mass fault code.

1. There is a one way valve situated at the back of the head (£35) that corrodes inside and can cause your issue.

2. Check for unmetered air entering the intake side (split vac pipes etc)

3. There is a flap next to the air filter housing that can restrict air flow if it is not working properly (I can't remember its name right now)

Start with the first two as they are the cheapest.

 

[Silverspa]

Thanks BlackC55, from what I've been reading on the web this seems to be a common thing with the C200k, as you say. I will get these checked out.

I am a bit miffed by the fact that my MB garage keeps telling me there is nothing wrong without checking any of these things, knowing that they can make another £50 when the light comes back on in a couple of days. If I knew how to do it all myself I would! It's frustrating because apart from a sluggish accelleration when overtaking (don't know if it is related?), I have noticed no other issues with the car!

 

[BlackC55]

Take it to a specialist. Much cheaper than a dealer.

 

[tonyho8]

Hi Silverspa,

I know your reported this issue way back in June 2009.
Did you managed to address it? If so, what was the root cause? and what was fixed?
I assume the car is no longer suffering this problem?

I ask this because I have the same fault code reported.
I've changed the O2 sensor and cleaned the MAF. However, I am still getting the same fault error code. Hence the reason why I was curious to see how you have addressed your issue.

Your feedback would be much appreciated

Thanks and regards

Tony