P0101 code on 2009 W212 E220, OM651

[occurs_to_me]

Hi, Long time since I’ve been on here…suppose that’s a good thing.
I was overtaking a car and then lost boost.
Engine light now on.
Mechanics diagnostic shows P0101 Mass or Volume Air Flow “A” circuit range / performance.
The pipe from the intercooler towards the turbo area has a fair amount of oil residue externally at both ends, and noticeable play at both ends.
There are green o rings at both ends of the pipe but I don’t know if these are subject to deterioration?
Any thoughts on best course of action?
- replace intercooler pipe?
- replace MAF sensor?
(I’ve searched the forum, but only found one post of a similar problem, but no responses/outcome). Thanks.


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[occurs_to_me]

Ps…I couldn’t find any splits in the pipe.


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[Cole@MBS]

Boost pipes are Very very common, don’t think I have ever changed a airmass on that engine, only way to really check is to boost the engine up under load with someones head under bonnet, or remove the pipes and check that way!

 

[frubpato]

I had that code when i had a split in the plastic inlet manifold - needed a smoke test to find it

 

[occurs_to_me]

I’ve had the intercooler hose on the drivers side changed (even though there were no obvious splits in it).
Mechanic has checked the other hose and it’s fine. He doesn’t have a smoke machine, so we’ve agreed it’s best to take it to someone else who has, and possibly more used to the foibles of mercs.


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[occurs_to_me]

Merc mechanic diagnosed problem as a faulty dpf sensor.
He’s replaced it and drove the car for a while, and says it’s all working fine now.
Due to pick it up tomorrow .


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[mersum1es]

Again a good example where MAF fault is actually totally something different. Interpreting codes will be x2 harder if reader is autocom or something like that.

 

[supernoodle]

Good luck, I can't see any relationship between the DPF pressure sensor and MAF.

 

[mersum1es]

Good luck, I can't see any relationship between the DPF pressure sensor and MAF.

Well, if mass flow values and pressure difference over dpf does not match in theory, either its pressure sensor or mass sensor, if it is not actual block in dpf. But still, it should have triggered dpf related code (if code reader DID read it right... tale does not tell which device was used).

Usually MAF codes are sourced by boost leak.

 

[occurs_to_me]

Mechanic No. 1 (not MB specialist) used a sealey code reader, that only picked up P0101 code.
After I’d left car with mechanic no. 2 (Specializes in MB), he rang me about 6 hrs later to say he’d sorted the problem.
My recollection of the call was that he believed the dpf sensor was faulty. He had read the P0101 code but also another code (sorry, I don’t know what it was, nor what reader he was using) which prompted him to look at the dpf sensor.
I think he done a forced regen, but on completion, the figures he was reading didn’t tally up with what they should be.
So….he replaced the dpf sensor and all is running ok at the moment.
Ok, I know there are some missing bits of info in the story, (from a phone call late Last Monday evening), but fingers crossed, the limp mode won’t reoccur.


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[supernoodle]

Ok, that makes more sense

Well, if mass flow values and pressure difference over dpf does not match in theory, either its pressure sensor or mass sensor, if it is not actual block in dpf

Dpf pressure sensor is only a delta pressure sensor. It only knows delta, nothing about the absolute pressure. So there is no way you can do any plausability check with the MAF.