MB CLK 208 Air Mass Sensor Fault

[zanzan]

Hi Guys,

I am an owner for CLK 208 MY99,i have changed original bosch air mass sensor 4 times during one year.

Honeslty NO one knows in my country what is problem?

What i feel now while driving the car: no engine power ,wrong up/down gear shift!!!!


Can some one help please with some more explanation and feedback about this problem and what are the solution which i can do in this case and what to check?


Thanks alot


zanzan

 

[Aussie Nick]

Sounds a lot like the air mass flow meter. When they replaced it on the previous four ocassions was there any improvement immediately after replacement?

 

[zanzan]

yes it works but for few days and then it came back with the same issue!!

thx

 

[Aussie Nick]

Ok I will see what the Aussie mechanics say and come back to you in a couple of days unless some other member provides the answer which is more than likely. It is obvious that the primary cause is the failure of some other part thereby corrupting the air mass flow meter.

 

[jberks]

2 posibilities come to mind. Firstly that there are cheap (crap) sensors on the market - are you definatley getting a proper Merc/Bosch part?
And secondly if it is genuinly failing then something is killing it. The most likely cause is contamination but this should be obvious from the condition of the pipe. I wonder whether an electrical short could be causing this issue and burning the sensor out. For example, the sensor has a quick heat up cycle to clean itself. If this is running too much, I guess this could kill the sensor.

 

[television]

2 posibilities come to mind. Firstly that there are cheap (crap) sensors on the market - are you definatley getting a proper Merc/Bosch part?
And secondly if it is genuinly failing then something is killing it. The most likely cause is contamination but this should be obvious from the condition of the pipe. I wonder whether an electrical short could be causing this issue and burning the sensor out. For example, the sensor has a quick heat up cycle to clean itself. If this is running too much, I guess this could kill the sensor.

Noting that this car is a compressor then oil could be getting onto the MAF there are some modified breathing pipes I believe

 

[zanzan]

yes its an original parts and i used to buy the 4 sensors from the MB dealer.

but i notice something while driving sometimes it works and sometimes it not.

I feel that through the accelerator while driving.

Once u feel the car flying and once its like truck.!!!

 

[Aussie Nick]

I tend to agree with Malcolm that there is possible corruption by oil contaminating the sensor.Yet, your mechanics would be able to readily observe that this was the cause. Maybe there is something to be said of the Jberks proposition that it is an electrical fault as the oil corruption theory would have been easily detectable by your mechanics yet they are puzzled by the cause .Obviously diagnostics has been tried and failed to analyse the source of the problem but surely if it is an electrical fault as proposed by Jberks the diagnostic computer would have detected this. What you describe is clearly A fault instigated by the failing air flow meter .

 

[jamesmc]

Zanzan

How many miles/km's has the car done?

 

[zanzan]

jemesmc

116,000 mile on it.

I have changed sparkplugs,oil felter,fuel filter,belts,oil,brakes,dics etc...

Its giving me hard time man.really i don't know what is the problem.

some people they are saying exaust system problem and it effects the air mass sensor so i am losing the power of the car because its made by lorinser.dunnooo..

 

[nuppy]

I had a simular problem on a Renault and it was a corroded earth wire causing a high resistance in the air flow sensors burning them out.

 

[television]

Do what the last chap did and unplug the MAF and take it for a ride

If you do a search here Jim in Essex did many post on this problem

 

[jimsinessex]

Look for the post entitled "oil in air intake", it goes right through the whole saga.

A CLK with that sort of mileage is very likely to be suffering this problem and will keep contaminating the MAF sensor. However oil should be evident at the sensor.

Jim

 

[Aussie Nick]

I think the solution lies in having a detailed analysis carried out on at least two of the previous failed air mass sensors. Did you keep them? It probably does have something to do with the supercharger. But I will try to get some opinions for you. Some other member will probably offer a worthwhile solution, However you need to supply more info about the condition of the air flow meter (air mass sensor). I test drove an E320 here which ran fine until you booted it down. It then started to shudder and miss until it stepped down a gear . I was told later that the AMS was the cause.

 

[jimsinessex]

I think the solution lies in having a detailed analysis carried out on at least two of the previous failed air mass sensors. Did you keep them? It probably does have something to do with the supercharger.

If the MAF sensor HAS failed due to oil contamination it will NOT have anything to do with the supercharger, this is an oft repeated myth that earns dealers and some indies a fortune. The kompressor has NO oil supply other than a very small amount in the sealed gear chamber.

Check for oil in and on the outside of the MAF sensor housing and also in the air filter top cover (that is after the filter element itself). It may appear to come from the breather on top of the rocker cover but the fault actually lies with the breather system located under the inlet manifold.

At the mileage quoted it is almost a certainty that the low to upper part load crankcase breather system under the inlet manifold needs replacing. The pipes become brittle, the nozzles block up and the small valve can block and jam. The parts are only £20 but labour is several hours as the inlet manifold has to be moved. Jamesmc did it himself and posted with pics, search under his name.

Jim

 

[jamesmc]

I think you will find that jiminessex and I are thinking along the same lines here and would suggest that the thread you may wish to read is this one:
Oil in Air Intake

From what I have read it seems that any CLK 230k over say 90,000 miles (or there about) is already suffering, or will suffer, from the problem of MAF oil contamination at some point and even if the lower part oil breather system becoming clogged is not the cause in this instance the repair/maintenance should be tackled anyway because no matter what you do now it it will be a problem very soon.

Jim did a lot of groundwork on this and that certainly pointed me in the right direction. I tried to compliment Jim's detective work that by adding a few pictures and an explanation of how I carried out the job on a DIY basis.

I also agree that, for the above thread to be the reason for repeated MAF sensor failure, oil will be present at the MAF sensor itself. If you take a look and there is oil there then, given the mileage of your car, it would be a fair bet that the cause is down to the lower load oil breather system being clogged up.

In which case you should replace the crank case oil breather check valve & hoses (lower part system under the inlet manifold) plus replace (or clean) the two brass breather nozzles incorporated into the system. The inlet manifold need to come off for this operation. Again see the thread mentioned above for more information.

Images can be seen Here in Reply #59

 

[jamesmc]

If the MAF sensor HAS failed due to oil contamination it will NOT have anything to do with the supercharger, this is an oft repeated myth that earns dealers and some indies a fortune. The kompressor has NO oil supply other than a very small amount in the sealed gear chamber.

I looked into this also and agree 100%.

 

[zanzan]

Guys,

In my Car there is no kompresser to check and there is nothing to check reagarding oil leak.
Its CLK 320.MY99

 

[jamesmc]

Guys,

In my Car there is no kompresser to check and there is nothing to check reagarding oil leak.
Its CLK 320.MY99

......aaaah!

 

[jimsinessex]

Ooops

Guys,

In my Car there is no kompresser to check and there is nothing to check reagarding oil leak.
Its CLK 320.MY99

Just for other W208 and W202 owners that may end up here after searching for MAF contamination solutions all the breather info is also relevent to the non kompressor four cylinder petrol engines as well, the kompressor being a complete red herring in this matter.

Jim