C200K, recurring check engine light, 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!!

 

[blueskies_6]

Hello

I had the same problem on my C200K. The first time, i was told that the system was "confused" and that there was no problem. It produced a small "f" on the diagnostic system, relating to the air mass meter.

I was told that a small "f" was fine and that if it had been a capital F, that the air mass meter needed replacing.

I also paid around £45 to have the memory cleared and it was fine for a while.

It then came on again and gave exactly the same code. The garage (a MB secialist, but not a dealer) suggested changing the petrol filter, as this could have put strain on the air mass meter.

That done, the memory was cleared again and it has not come back on since - even after a few long trips.

Hope this helps.

Peet

 

[Silverspa]

Thanks for the speedy reply Pete, I've rechecked and the mechanic actually replaced the Air Mass Meter (according to the receipt). I hadn't noticed the small f on the report before but I can see it now.

I will definately get the petrol filter checked out, as it the CE light seems to come on straight after a fill-up each time. I am surprised that my MB garage haven't suggested this but I guess it is not a very lucrative job...do you remember what the cost is, or is it something that a complete novice like me could do?

 

[television]

Do pull off the wiring connector on the very front of the engine and see if there is any oil in the plug, its the camshaft adjuster plug

 

[blueskies_6]

I wouldn't do it myself to be honest. I am pretty sure it was around £100 - £150 including their labour.

Good luck!

Peet

 

[Silverspa]

Thanks Television (I've read lots of your posts and was hoping you would reply!), I am a bit clueless (and hence a mechanic's dream mark) with all this and am grateful for all the advice!

I saw a very old post for a very similar problem discussing oil in the loom, which had a pic of an SLK camshaft but didn't recognise it in my engine, I will have another look tomorrow in the daylight and see if I have any luck with that. Do you think it could be oil on the sensors, and if so is this a serious / pricey problem? Apart from sluggish accelleration I've noticed no other problems with the car.

 

[television]

I am not sure if this does affect your engine but do have a look just in case, if there is one and there is any oil in it you can get a blocker that is fitted in line

 

[Silverspa]

Am a bit terrified now as I've been reading posts about the C200k and have turned up all sorts of possible problems, not least a radiator / transmission fluid problem. I don't think that will affect my car (2037452***) but now I'm a bit worried, can anyone confirm whether this could affect me and if so what preventative measures I should take?

Also does anyone know what MPG I should be expecting for city driving (I think around 35?) so I can work out whether my fuel consumption is unusually high?

 

[Silverspa]

Update

So I checked the cam plugs and yep, there is a load of oil in there.
Have found a local Merc specialist so will take it there, does anyone know the name of the blocker I need fitted, and the cost? Is this a cure, or a workaround?

I also got the DAS report back today, the only F on there is the air conditioning, (B15AB) which I know needs re-gassing (but did not want to pay the £200 MB wanted when others are charging £45!) and I will do tomorrow - does anyone know if this will cure the CE light?

Finally the sluggishness with accellerating seems to be intermittent and not that bad at the moment, but there is a stored fault on the readout:

P201D-004 Self Adaptation of mixture formation, mixture too rich at idle speed - does this mean the oil has gotten to my O2 sensors?

Thank you so much for your help!

 

[Cole@MBS]

That normally means airmass sensor, oil in the loom can knock out the 02 sensors as its the lowest point of the loom, last harness change i did, i changed the 02 sensor just to make sure!!

 

[television]

You can put the blocker on your self, it cost about £35 you just plug it in to the sensor and put the existing plug back into the end of the blocker. You should check the ECU to see if any oil is in there, if so take it out and wash it in lighter fuel, let it dry and put it back,if any oil was worked its way into the MAF then clean it out. If the engine has been burning any of this oil the the O2 sensor may have shifted from its stored setting. If the oil in the loom is not too bad it may all just go away

 

[Silverspa]

Thanks Sam - had the 'Airmass Meter' changed when I bought (Dec 08) after the DAS threw up the code PB200B-004, DAS report from last friday and previous reports have not shown that code again... Is the Airmass sensor the same thing as the meter, or something different?

 

[television]

MAF or MAS all the same thing, its called a meter as it meters the air flow going into the engine

 

[Silverspa]

You can put the blocker on your self, it cost about £35 you just plug it in to the sensor and put the existing plug back into the end of the blocker. You should check the ECU to see if any oil is in there, if so take it out and wash it in lighter fuel, let it dry and put it back,if any oil was worked its way into the MAF then clean it out. If the engine has been burning any of this oil the the O2 sensor may have shifted from its stored setting. If the oil in the loom is not too bad it may all just go away

Thanks Television, can you recommend a site where I can get this part for my W203 engine (part number would be immensely helpful if you have one ? I think I am ready to try tackling this myself!

There doesn't seem to be much oil around the engine but then what do I know :???: hopefully I have caught this early thanks to you lovely people posting past advice!

 

[television]

Its a MB part only and should be a stock item

 

[Silverspa]

Does anyone know if 21 mpg is a good or bad average for city driving for a W203 C200K? I've only just started commuting in the car (used to get the tube) so not sure what I should expect from it, 21-23 mpg was showing on my trip home tonight.
Thanks

 

[Cole@MBS]

Thats not good!!!

 

[blueskies_6]

I don't think you'll get 35 mpg city driving. I get that on the motorway. Depending on traffic, i'd say anything above 20 mpg is good.

 

[Silverspa]

Thats not good!!!

Thanks chaps, I found a review (admittedly an older C200k) which put the mpg at about 29 and not MB's stated 35 mpg, so given my stop starting in London traffic all the way home, although (as you say Sam), it's not good, sadly I don't think it is unusual! :lol:

 

[Silverspa]

You can put the blocker on your self, it cost about £35 you just plug it in to the sensor and put the existing plug back into the end of the blocker. You should check the ECU to see if any oil is in there, if so take it out and wash it in lighter fuel, let it dry and put it back,if any oil was worked its way into the MAF then clean it out. If the engine has been burning any of this oil the the O2 sensor may have shifted from its stored setting. If the oil in the loom is not too bad it may all just go away

MALCOM (Television): not sure if you are still reading this, but I phoned MB today with your advice and they claimed never to heard of the blocker and that the part doesn't exist, they offered to order me a solenoid instead, apparrently that is what they have replaced for other C200k with oil in the plugs. They didn't sound surprised about the oil, which is surprising to me as they have not mentioned it once in 3 visits, and keep telling me nothing is wrong. I can't help feeling they are waiting until it is a serious problem and can replace whole the harness, perhaps I'm being oversensitive but I can't see why didn't they notice this themselves if it is a known problem with C200K's?

Getting the AC done tomorrow, hopefully that will switch of the CEL and buy me a bit of time to do some more research on the part