There appear to be 4 parts that when they go bad on a W208 can cause the car to idle rough or hunt up and down, stall, and eventually die. You most likely will experience a check engine light (CEL). Based on others comments and posts, I have narrowed the possible problems to the following items, though there are certainly others:

(2) Air Mass Sensor
It is possible that the AMS is dirty or bad. You can clean the Air Mass Sensor (Aka Mass Air Flow Meter or MAF) and see if that makes a difference. If it needs to be replaced I can get it from $191.00 at Importecparts.com as well. Install takes about 10 minutes. Do not pay the dealer for the part or to replace this item if you don't have to.

(1) Crankshaft Position Sensor
You may find it hard if not impossible to locate a "Crankshaft Position Sensor" online because it is refered to as a "Reference Sensor". The dealer wants for $125.80.00 or so for this part. I found a site http://www.importeccatalog.com/) that has it for $91.00.

(3) O2 Sensors
These are fairly easy to replace as well. The dealer wants around $225.00 for these parts. You can get them from Importecparts.com for around the prices below:

Oxygen Sensor: Left Front
Located before catalyst
Cost: $155.20

Oxygen Sensor: Right Front
Located before catalyst
Cost: $155.00

Oxygen Sensor: Left Rear
Located after catalyst
Cost: $143.90

Oxygen Sensor: Right Rear
Located after catalyst
Cost: $115.70

(4) Fuel Filter
It appears that you can replace this in about 20 minutes and the part is $32.30 from Importecparts.com.

 

When I take my car out of its winter hibernation... I will surely perform all of the following as a preventative measure... thanks for the info...

 

Mine feels like it's about to stall at a stop sign or red light but only when the engine is still cold. Any idea what the culprit could be? No check engine lights at all and it won't do this when the engine is warmed up. I also just had my MAF changed recently. Doesn't do it all the time either. If I take it to the dealer they will probably not find anything b/c the symptoms are so mild right now.

 

If the dealer changed the air mass sensor then you should notify them you still have problems. Notice is always good. If you changed it then make sure the AMS is securily seated and the air box is on tight with the AMS. You should also read the OBDII codes to see if there are any and don't just rely on the Check Engine Light. Good luck.

 

I am in different country (UAE) and any car repair company I go to have the part removed and let me clean it, will not do it. They all state that the part has to be replaced. I don't really feel like forking out as much as $1000 for repairs. I got my MAF sensor checked the Mercedes Dealership who said it was faulty. I did not get any malfunction signal at any point. Only problem I was facing was the car dying at lower speeds occationaly. I don't even know where the MAF is located. Can anyone please help me?!?

 

From a previous post of mine:

Two weeks ago my car threw a check engine light (CEL) and had a hard time keeping a constant idle at 600 when I would come to a light. It would drop to almost 0 and then spike to 1000 trying to reach a constant idle rpm. It seemed to drive fine once it was going but coming to a stop and then starting again was exasperating to say the least. The car would most likely die.

From reading others posts the problem appeared to be the Air Mass Sensor ("AMS") also know as the Mass Air Flow Meter ("MAF"). Sure enough the OBDII code was P0100 for the MAF or VAF circuit failure. Others have referenced codes P0170 - Fuel Trim Malfunction (Bank 1) and P0173 - Fuel Trim Malfunction (Bank 2). However, I didn't see these codes. You can have the OBDII codes pulled for free at AutoZone or Checker.

I removed the old AMS (MAF) in around 20 minutes. The steps are as follows:
(1) Remove the front engine cover with the Mercedes star on it by pulling up.
(2) Remove the left and right air intake tubs that run into the air filter box.
(3) Pull up on the air filter box which is held in place by four ruber gromets.
(4) You will then see the AMS (MAF) at the back of the engine.
(5) Unclip the plug on the right hand side of the AMS.
(6) Unclip the left and right plastic arms of the ring that holds the AMS onto the engine block. It can and should be completely taken off the AMS in order to more easily remove the AMS from its holding tube.
(7) Use a flat head screw driver (longer is better) and push the metal clip away from the AMS (the clip is attached to the holding tube) so that it can be firmly pulled up and out of the holding tube. I had to wiggle it back and forth gently and up at the same time. It took some effort but it does just slide out. You may notice that the tube it plugs into, which goes into the engine may also move when you try and remove the AMS. Do not take this part off- only the AMS should come off.
(8) Reverse putting the parts back on (this took about 1 minute).

Fired the car up and it immediately idled properly. After three cycles of starting and shutting the car off the check engine light disappeared. Problem solved.

I purchased the AMS from autopartswarehouse.com which price matched Importecparts.com in the amount of $191.00 (price included free shipping). The Dealer quoted me $384.00 for the AMS alone and then install was over an hour at their hourly rate. What a rip off! Everyone should do this repair themselves and put the saved cash into other modifications.

I have attached a picture of the AMS, which is dealer part#1130940048 for the 2001 CLK55 AMG. See picture here.

 

Got my ignition wire plugs replaced ($350 but I got a discount). Will let you know if this does NOT fix the problem. If I don't post on this thread again then it probably worked out.

 

Hey guys I'm new to this forum. I just bought a 2004 CLK 55 AMG like a week ago and starting to have trouble. My Check Engine Light is on and i don't know why. I found this website as a result of my research. Why a car of this magnitude having issues at only 64k miles??? Maybe I am a bit naive, a rookie or all of the above but one would think that for what is spent on a car like this...it should have very few problems. I saw some of the 4 possible fixes which I found to be very helpful but wish someone could have posted the actual pictures of the work being done on their car. Are the 2001-2004 CLK 55 AMG models the same under the hood? If not, what are the differences? Oh yeah are any of you in So Cali? I will post pictures soon...please respond anyone.

 

You could do all four procedures listed and not fix your particular problem. When the check engine light comes on, a failure code is stored. There are scores of codes. An OBDII code checker will tell you the failure code, which is used to determine which part should be replaced.

One difference between the W208 (2001/2002) CLK55 and W209 is the W209's have higher compression.

 

Thanks Marcus! I thought no one would ever respond. So now I guess I could get a diagnostic test run and that should point out the failure code. This appears to be common with Mercedes. Please excuse my ignorance but what is W208, W209 etc? Our these codes?

 

W208 is the body style such as "MarcusF"s vehicle which was produced from 97-02, W209 is the newer body style such as mine (see below), which is produced from 03 - present...welcome to da forum!

 

Here in SoCal, most Kragen auto parts stores will run the OBDII test for free. The OBDII tool is about $80 now.

 

Thanks DBL. That's one nice ride by the way. I took the CLK to the dealer and after they ran their test it turned out my gas cap wasn't secured! Silly me wheww...no serious issues. I'm looking to upgrade my wheels from the stock 17's to 19's. I think 20's are bit much and makes for a rough ride. From what I've heard, 19's would be a perfect fit. What size tires do guys have and what do you think of 19's on the W209?

 

no prob. and thanks for the compliment...19's would be the best i believe...i assume thats what most of the folks who frequent this forum run on their vehicles...