Hello. I have Check Engine Light (CEL) + Limp Mode (LM) on a W212 facelift (WDD2120021A872996 -- OM651 @ 170hp). Took it to indie mechanic with STAR for diagnosis and got these:

- P246309 -- DPF soot content too high
- P227962 -- Air Intake leak on the inlet Manifold
- P228100 -- Air Leak Between MAF and Throttle Body

We started DPF regeneration from STAR (value was > 200%) driving at 2500rpm. Normally, 7G won't keep 2500rpm (except in D7 at high speeds), but in LM it shifts at ~2900, so 2500 in D1/30km/h was doable. After 15 min, DPF was left with 1% -- operation successful.

Mechanic said DPF regeneration had failed 3 times (had been driving 1 day on low fuel) and it would only be reattempted manually from STAR. And that the DPF error caused the other errors. His theory held 2 KMs until CEL came back (P227962 + P228100).

Then he tried unmounting the air filter, blewing some air under pressure in the intake area -- still no results. We disconnected the MAF sensor and received expected errors in STAR, so MAF connectors seemed fine.

Mechanic's final verdict was to check/replace all hoses and gaskets starting from MAF sensor going to turbo, intercooler and towards throttle body. I find this approach time/money consuming and I might not discover the problem after all. I am thinking to get the car to an authorized MB dealership for a check/diagnosis/repair, even though it will run me much more expensive. Do you think it's worth it? Is there something else I could check? Are these error codes common?


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2-3 days before the first sight of CEL, I sensed the car was not OK. Symptoms were:

- it would sometime "drown" for couple seconds until gearbox shifted up. "Drowning" I mean like the engine going on and off very fast with the tachometer oscillating 100-150rpm up and down. I know this explanation sucks but I can't describe it otherwise. It would create a sensation the engine "suffocates" and if I had for example a drink in a cup it would definitely spill over because of the "ups" and "downs".
- cruising normally sometimes the car would feel very sluggish and then suddenly out of nowhere, it starts to rip off the asphalt, without me modifying the acceleration at all!

Both issues happened rarely and unexpectedly. I even tried to reproduce sometimes and I couldn't. Then after 3 days, CEL + LM came on. In LM, they never reproduce, but I guess that's because of the different way the engine/transmission work when in LM. I think both issues are kind of the same, but in the first one the power comes on and goes out very frequently, creating the up/down sensation.
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What do you guys think? Thanks a lot!

 

Recheck DPF after car restart.
I had my iCarsoft scanner performing regeneration, showing sot coming down to 0, only on restart showing the number was bogus and DPF was still clog.
Intercooler leaks are easy to spot as they leave greasy residue around.

 

After DPF regeneration and codes clearance, when CEL came back, the new codes were only P227962 and P228100. The value of the DPF was also still 1 something %. So I don't think that's the case.

I will visually inspect the intercooler hose to see if there's any greasy residue though...

 

Hi,
Appreciate this is an old thread and I'm just hoping you're still active.

Did you get to the bottom of this, as I am suffering EXACTLY the same symptoms and errors as you describe.

Thanks

 

Hi, yeah, the culprit was this hose:
Well not exactly that model, but that part had a tiny fissure and that caused loss of pressure from the turbo and hence all the other symptoms.