C270 Limp mode and not MAF SEN

[MBC270]

Hi All,

I am new to forums but I have a problem that I just don't have a clue what to do.

I have a 2002 c270 cdi W203 and is in constant limp mode.

When on diagnostics I get the following codes:

P0100 MAF sensor
P1403 egr Valve
P1470 Boost Pressure regulation
P1189 Inlet port shut off.

It first started off going into limp mode intermittently but has got to the point in which it is in permanent limp mode. (Just to let you know I only drove my MB about 50 miles before going into limp mode permanently) I believed that the problem was either the EGR Valve, the ECU (because the cooling fan is on all the time), inlet ports or the MAF sensor.
I have fitted a brand new MB manifold, 2 new Bosch MAF sensors and a new ECU all which have still left me with the same fault codes. I have tested the voltage going from the ECU to the MAF sensor and all seems ok. I believe that it has to be something electrical but I have no Idea where to go from here. I am sure someone has a greater knowledge than me in regards to this problem.

From looking at forum's the only other thing I can think of is it is something to do with the gearbox but I just cant get my head round why it would be the gearbox if when on diagnostics the MAF sensor is showing 0mg/stroke??

If you could help or even give me an idea on where to go from here please help.
Oh Since I changed the ECU i get the following fault messages on my dash, coolant level sensor, which I have a new one but has not been fitted and stall error message. I do not know if these are linked but I wanted to give as much information as possible.

I just have no idea...

 

[BlackC55]

You need to check the wiring between the Ecu and the maf.

 

[MBC270]

Hi Blackc55, Yes I have checked all wires with a volt meter and they are all fine.

 

[MBC270]

Any other idea's. do you think it could be something to do with the tcm?? it is strange but only direction I can think i can go in..

 

[BlackC55]

I would expect the ECU to be faulty then

 

[E270 Owner]

As above....

But...

I have seen some of those fault code related to Turbo and or boost pressure related problems be it over boost or under boost.

Check the charge pressure side of the system and then the turbo.

 

[MBC270]

I have changed the ecu, barrel and esl and still in limp mode, so It must not be the ECU. I have checked the charge pressure and it seems all ok, I have been advised that it could be the transmission and have found out that it will rev above 3000rpm when in manual but then back in Auto it will not exceed 2000rpm. I can see how the transmission could put it into limp mode but then why am i getting faults relating to the MAF sensor and inlet port?? Does anyone believe this could be something to do with the ECU wiring as I replaced the coolant level sensor for a brand new one and I am still getting a coolant level error on my dash?? My coolant fan is also going 100% I know this is a sign of either the ecu or inlet port but both of these have been changed so I am not too sure where to go from here.

 

[ash59fifty-uk]

You mentioned one of the faults being an EGR one but haven't mentioned after if you checked it, did you clean it out?

Possible leak in one of the pipes leading off the EGR or the turbo?

 

[MOZ]

Hi,
Not sure if this is a stab in the dark and helps or not as I'm not totally familiar with the C270 (mines and ML270 but I believe are the same engine etc).

Are you sure its limp mode or just non turbo (NA type mode) I ask because afaiaa limp mode would restrict the revs, whereas you say in manual you can go past that. I had a similar situation to you where mine was very sluggish and wouldn't rev past 2000 to 2500 rpm when in auto but would in manual and i thought i was in limp mode but wasnt (It was different to when my car did go to propper limp mode after a boost pipe popped off on another occasion) and my problem was that one of the vaccuum pipes around the Boost pressure control vacuum transducer had come off. reconnected it and whamo, back to normal.
If you havent checked that area yet, worth taking a look to see if teh pipes have come off or have split.

The following is taken from another thread i found relating to it but is based on the ML so I don't know if the location is the same on the C class, but there is a big black plastic spherical thing on the inner wing of the drivers side (of the ML) that's where it is on mine:



The diagnostic code for this problem is1470

This is the code relating to a Boost pressure control vacuum transducer and the symptoms are that the ECU turns off the Turbo and the engine becomes normally aspirated, hence slow acceleration and slow top speed.

The Boost pressure control vacuum transducer is located in the front left of the engine compartment, just in front of the black semi-ball unit, has 2 pipes going into it and at the base, has what looks like a fuel filter, but is actually the atmospheric pressure sensor input.

On my car, bad contacts where to blame. Disconnecting the unit whilst the engine was running switches the engine into the normally aspirated mode described above.


Hope this helps. Good luck
Kind regards.

Moz

 

[MBC270]

Hi Moz thanks for the feed back. The c270 has two vaccume pumps one on the right by the coolant bottle and one on the left near the manifold. I have looked at both but it is worth a try. I am not too sure why I would be getting other codes i.e. Maf sensor and inlet pot. Yes the car will rev past 2k in manual but i still think it limp mode as although it rev past it still does not have anywhere near the power it did or should have. I think I gotta just get it onto star and go through everything on it. such a shame as only had the car a few.months and only got a c270 because some idiot decide to write my overone off and didnt have a problem with her at all. Anyone know an indie in northern ireland??? or will I have to take it to mercedes???

 

[C250TD_Auto]

have you checked the wire connection on the autobox - this connection is known to leak and the fluid can travel over the wires into the loom/ecu - there's an easy check you can do with the car on a ramp - check out the Mercedes Source u tube channel https://www.youtube.com/user/Mercedessource