ziwe

I have this really annoying problem.

The car has started to give me this error code when these conditions are met:

- Engine is heated up.
- I drive at 125-140 kmph
- it seems kinda random how fast it shows
- sometimes it is accompanied by a P0124 - throttle position sensor
- i feel a sudden small ... well like the car just misses a beat, and then it is in limp mode with engine light on. engine light stays on until cleared, but limp mode is gone at next start.

The error is differential pressure sensor to low on dpf.
I tried to change the sensor (it is quite a pain) but this did not change the behavior.

Running with a ODB scanner online while driving, i can see that values seems ok, i get airflow in g/s that seems quite jumpy, even when i run at steady speed on a straight road (it will give jumps like from 70 g/s -> 150 and then back down), but im not sure if this is normal.

I really like some input on what my next move should be.

my own thoughts are :
- possible bad wire/connector to the DPF diff sensor, i have sprayed it with contact cleaner and termnials seems ok, but the wire was fixated with a strip around the original sensor, is this standard? or mayby it could be an indicator of previous issues.
- throttle valve is blocked / covered in sod ( as i understand it, exhaust re-circulation passes this, so it could be quite a mess after 190000km)
- MAF sensor might be bad - my guess here is that the ECU must calculate the P244A by a air in/ air out approach on the engine, if MAF is sending random high peaks, then the calculation would indicate that diff pressure over the DPF is to low.
- The speeder pedal it self - as indicated by the sometimes occuring P0124 ... problem here is that i get really smooth and good readings from this, also the error is indifferent from if i drive in distronic mode or manual.
- Maybe the ECU just needs to calibrate new Diff Sensor? (wishfull thinkiing).

any help is much appriciated, thank you

ziwe

I have been searching the car for leaks, including beeing under the car to check the DPF and connectors to the diff sensor, they look like new, and there seem to be no leaks here what so ever. Nut there seem to be some kind of leak near where the air inlet hose is connected to the turbo, i have a buildup of residue around this connection, it seems worst on side facing the engine. there is a smaller hose packed with heat protection that runs up on the top of the engine that is connected around here (from EGR ?). as there is residue it cannot be from the clean air from the filter box, but have to be from somewhere else, could it be from this smaller hose? i guess recirculated exhaust would be able to make this kind of buildup when it has not ben through any kind of filtration, but i would think that this area is not prone to leaks as it is before the turbo...

ziwe

Problem is the turbo / intercooler hose. Noticed some small imperfections near the turbo. After a good amount of ducked tape the problem is gone. I have ordered a new hose. So P244A error code can indeed have a root cause in the air inlet system!

FLASHBACK

Sorry for the late question but did you change the hose and did it solve the problem?
Do you have the Mercedes spare parts no for it?
Best wishes

ziwe

I did, and it didn't .

But, changing the dpf sensor as well as the connector to it did! it appears to be a common issue, as they sold many places with a pigtale for soldering on to the wire harness.
I used this one from E-bay and it works - https://www.ebay.de/itm/264290464775

And very fine that you asked, now people can find out what actually solved the issue

FLASHBACK

Great!
I myself is about to change the DPFsensor due to DPF differential sensor errorcodes..

ziwe

I strongly suggest changing the connector as well, i changed the sensor 3 times, as it seemed to solve the issue for like 3-4000 km.

FLASHBACK

Do you have any theories to how the connector gets bad?
Are there movement in the cables back there?

ziwe

My guess i that the vibrations from the motor over time damages the wirecores near the connector due to metal fatigue and a result in loose connection at some specific rev range, therefor the sensor cannot measure the diff pressure properly and over time the sensor will get damaged due to the constant jitter in power supply.

It is a common issue i have learned, and it clearly solved my issue to change both sensor and connector. If it solves your issue we can only hope.

FLASHBACK

I will begin with the sensor, step 2 is the connector.
Thanks for the help!

20231225 UPDATE:
Replaced the sensor and all is "A OK" the car runs at its best and no errorcodes whatsoever.
Happy Holidays!

FLASHBACK

Darnit, today it happened again. Im gonna replace the sensor AND the connector as well.
Exactly as you said ziwe 3-400km for me as well.


4th march Update
Replaced the Sensor and NO GO!

Is it somehow possible to measure the sensor for function without having specal equipment, I have a multimeter..

Is this a known by Mercedes problem as there seem to be an updated connector and a repairkit?

FLASHBACK

Can you please explain how to replace the connector?