C204 2011 C220 CDI COUPÉ LIMP MODE & EML

Hey guys,

hope all of you had a great week so far!

About two months ago the EML of my car turned up and being checked by the dealer. No unusual signs beside the Auto Stars/Stop (Eco System) stops working completely at that time. I was told that the Boost Pressure Sensor & the auxiliary battery had faulty (see photo attached) so got them replaced which costs me approx 350 quids. It drove like a dream afterwards until today, this morning, the Engine Management Light turned up again! After I started the car this morning I immediately noticed the engine idle speed is now much higher than it used to be (was around 6-800 RPM but now runs at 1k RPM). Strangely, this time the Eco mode still works but looks like the car goes into limp mode. On the way heading south this afternoon the car was running noisy due to changed gears at a higher rev (always changed at a speed more than 2k regardless the gear selected) than it used to be (1400-1600 RPM); and the car has very sluggish acceleration now. I was thinking of blocked DPF and the car might needs a long run to have the DPF Regen done when I first discovered the engine light and unusual signs this morning, so putted a bottle of Redex DPF cleaner before setting off south to have a long motorway run. After 100 mls run the car still under limp mode and nothing changed... Don’t know what’s happened there, anyone has any idea on this?

 

Check your boost pipes for splits.

 

Have booked in with a local garage for next Monday, will ask them to check this if possible

 

If you have a boost leak it can impact the ability of the car to do a regen.
Common boost leaks are split turbo pipes (can be hard to see), snapped inlet manifold bolts and cracked or holed intercooler. All these can give low boost symptoms.

 

I would not be guessing too much. To use diags tools one needs a lot of experience to look at different parameters under different conditions to eliminate certain things and find the culprit.

Use a good merc indy with the right tools otherwise you will be throwing money at parts till one actually does the trick.

There are many things trigger the EML or the things you suggest and need eliminating.

do post back the result .

 

Hey guys,

quick updates after the car being stuck in the garage for about a week...

Three days ago the car went through a diagnosis and found three error codes (Faulty MAF sensor & Faulty Exhaust Back Pressure Sensor 1 & xxx (sorry can’t remember flaps not operated )I have been told that the car had a faulty MAF Sensor which caused the other two error codes. The replaced sensor hasn’t arrived until this morning. So got it replaced and the garage test drive the car for a while and handle it back to me said it’s okay for now (420 quids gone). However, on the way driving back home, I can still feel the sluggish acceleration although the Engine Management Light was off. As soon as I arrived home and parked up the car, guess what, the Engine light back on again! Therefore immediately sent the car back to the garage and asked for a quick check. After waiting for a while, they told me that although they found no leak or spilt pipe two days ago when they did the smoke test during the diagnosis, there may be still a pinhole exists which cause the pressure leakage therefor they will need to take apart components under the engine bay to have a throughout check...

It’s really annoying now and don’t know what happened there... finger crossed they can find something and get the car back to normal soon

 

hi tgl3 - reading your post is almost exact same problem i have. Car is 2013 but low mileage 45k but 90% on infrequent trips of 50-60miles so not a town driving problem. did you get a final fix? Many thanks

 

Hi Mark, yes I have managed to fix it It was found the replaced MAF sensor faulty(faulty OEM part supplied by Mercedes) and the Mercedes had sent another new sensor to the garage and has it replaced. No further issue discovered since the new sensor installed on September.

 

Many thanks for update. Much appreciated. Good to hear it is solved. will let you know how mine goes.