C350 2013 limp mode no engine lights, no boost/turbo

[Saeedk1995]

Hi, I’ve got a 2013 Mercedes c350, when I bought it it was already remapped. The problem I have is when I go on motorway drives, after about 30 mins it goes into a limp mode, but no engine lights come up, i feel as though it has cut the turbo out as the mpg and the boost decreases, i can still run the car at 70mph, also I cannot manually change the gears, once I get home and then the car off and on after a few minutes it’s working like normal again. I took it to a Mercedes specialist who recommended that I put the latest Mercedes ECU software. Did that and still had the same issue. Then he ran it on the STAR machine and said he was getting 0 reading on the dpf sensor so he suggested to change the sensor and wiring down there. Did that and still had the same issue. I’ve also changed the turbo temperature sensor and still didn’t fix anything. I don’t know where to go from here and without no engine management light he can’t pick up anything on his STAR machine. I was thinking if it’s something to do with the dpf regen, maybe it’s clogged up? Maybe a carbon clean could help, but not sure if I’m just wasting my money. I’ve noticed it occurs quicker when the car is hot, i.e on sunny days. Please can anyone give me advice on what to do or what you think could be the problem?

 

[john campbell]

I would get the car back into limp mode and DO NOT turn the car off so it can be plugged into a computer and then use live data to read what's going on. I had a similar problem with mine ( diff engine tho ) and found the exhaust back pressure sensor was at fault and after I changed that my problem went away. I'm sure your suffering with the same type of problem and if you turn the car off its just resetting the system.

 

[mattkh]

Hi, I’ve got a 2013 Mercedes c350, when I bought it it was already remapped. I was thinking if it’s something to do with the dpf regen, maybe it’s clogged up? Maybe a carbon clean could help, but not sure if I’m just wasting my money

What is the mileage..?

 

[Saeedk1995]

What is the mileage..?

107k mileage almost, probably has been happening since I bought it at 95k mileage

 

[Saeedk1995]

I would get the car back into limp mode and DO NOT turn the car off so it can be plugged into a computer and then use live data to read what's going on. I had a similar problem with mine ( diff engine tho ) and found the exhaust back pressure sensor was at fault and after I changed that my problem went away. I'm sure your suffering with the same type of problem and if you turn the car off its just resetting the system.

Thank you I’ll try do that it’s just difficult getting it to a merc specialist who will look at it straight away

 

[john campbell]

Buy yourself a icarsoft computer that way you can read it when it happens and post your findings. There are some great guys on here that will help you get to the bottom of the fault and if it is a sensor issue they are usually a DIY job so you could save £££££££££££

 

[sweeper]

i had similar issue with my R350, exhaust back pressure sensor was the issue, (this may or may not bring light on and may or may not store a code, however if you study the readings they will be off, sometimes reading correct and sometimes reading 0) did the dpf sensor cure the 0 reading on the differential? If not then the pipes are blocked or split or possibly the dpf had been doctored, in which case you will have a problem now the software is back to normal as it may have had a dpf delete.

 

[Saeedk1995]

Buy yourself a icarsoft computer that way you can read it when it happens and post your findings. There are some great guys on here that will help you get to the bottom of the fault and if it is a sensor issue they are usually a DIY job so you could save £££££££££££

Thank you, I’m going to get it check out whilst the problem is happen, I book a diagnostics with a merc specialist in Manchester so driving hopefully the problem will occur and they can see it live.

 

[Saeedk1995]

i had similar issue with my R350, exhaust back pressure sensor was the issue, (this may or may not bring light on and may or may not store a code, however if you study the readings they will be off, sometimes reading correct and sometimes reading 0) did the dpf sensor cure the 0 reading on the differential? If not then the pipes are blocked or split or possibly the dpf had been doctored, in which case you will have a problem now the software is back to normal as it may have had a dpf delete.

Thank you very much for the advice, much appreciated. I’m not sure about the technical side, I just gave it to the garage and they told me their findings, something to do with 0 dpf reading. I’m going to a merc specialist tomorrow whilst the problem is happening so they can check it straight away, I’ll pass the info I’ve received from this thread on and then feedback whatever they find on here.

 

[bembo449]

could easily be the turbo wastegate actuator but as suggested , get it plugged into , you don't necessarily need to go to MB indy as snap on or Delphi should diagnose the issue just fine ( I have both and icarsoft ) so just go to a garage and ask what they use for diagnostics

 

[Saeedk1995]

Just an update, I went to a garage in Manchester, it was just over an hour drive, the aim was to turn up with the problem live however, for some reason the car didn’t have the problem throughout the journey, when I turned up they plugged in the machine and said there’s nothing wrong with my car, everything was reading fine and dpf was at 7% so I just wasted a journey basically. The next day I went on the motorway and the boost went within 5 minutes. The day I wanted the turbo to not work it decided to work, so annoyed.

Although they’ve done diagnostics and saw that the car was running fine, could it still be a faulty exhaust back pressure sensor? Does that mean it can and cannot work sometimes? I’m not sure if i should change the exhaust back pressure sensor first and then the turbo wastegate actuator or vice versa to find which one fixes the issue first.

 

[Saeedk1995]

Further update: I’ve changed the exhaust back pressure sensor myself, still has the same problem so it isn’t that I guess.

 

[supernoodle]

I would suggest your car is not going into a forced limp home mode. They should not be able to do that without lighting the MIL and logging a fault. I can imagine you are being limited only because some signal is failing but in range.
You mentioned blocked dpf, but also after keying off and on, all its OK again. To me that would rule something like that out.
You also mention that it happens quicker when it gets hot. What happens if you let it cool down whilst still powered on? Does it recover? So is it the temperature or the power down that fixes it?
You mention you can't manually change gear. I'm struggling see why any sensor connected to the ECU would prevent that.
Transmission Control Unit does give a torque request to the ECU, so worth thinking beyond the engine.

As others have said, you need live data. That coupled with the facts of the event and some sound reasoning should get you closer.

 

[sweeper]

Hi did you ever sort this issue?

 

[sweeper]

I would suggest your car is not going into a forced limp home mode. They should not be able to do that without lighting the MIL and logging a fault. I can imagine you are being limited only because some signal is failing but in range.
You mentioned blocked dpf, but also after keying off and on, all its OK again. To me that would rule something like that out.
You also mention that it happens quicker when it gets hot. What happens if you let it cool down whilst still powered on? Does it recover? So is it the temperature or the power down that fixes it?
You mention you can't manually change gear. I'm struggling see why any sensor connected to the ECU would prevent that.
Transmission Control Unit does give a torque request to the ECU, so worth thinking beyond the engine.

As others have said, you need live data. That coupled with the facts of the event and some sound reasoning should get you closer.

You certainly can get restricted performance without the engine warning light, my R done it several times, there was a ti from MB which I found but only after it eventually did throw a light and record a fault, there were issues with wiring on the exhaust back pressure sensors sometimes recording faults and sometimes not was documented, the pressure sensors themselves were rarely at fault but changing them cured the problem by virtue of making a better connection when the new one was plugged in, pins should be checked both ends followed by replacement of the pins on the sensor plug, I’ll see if I can find the document again.

 

[supernoodle]

Restricted performance and limp mode are not the same. That's why I explicitly said "forced limp home mode".
Limp home mode is when a module has detected an error and purposely limited performance (usually by reducing a toque limit map) to prevent possible further damage. Note, not all errors will invoke this torque reduction. So you will not be in limp home mode without an error and probably the MIL.
If you have some component that misbehaves, but not flagging a fault, that could indirectly (eg fuel injector under delivering) or indirectly (eg pressure sensor giving false reading) reduce the performance.
If you're trying to diagnose a fault, to understand the difference is important.

 

[LostKiwi]

The other thing that may cause this type of issue is a bad MAF. That would also give gearbox issues. Using a diagnostic box to monitor live data will help diagnose this issue.

 

[Saeedk1995]

Hi did you ever sort this issue?

hi, yeah I did, it happened to be the DPF, apparently it was falling apart inside, the mechanic stuck a camera in there. So he removed the DPF and remapped it and that sorted the issue. I’ve drove it on the motorway a few times now and I’ve had no issues.

 

[Saeedk1995]

Really annoying bc I must have spent around 1.5k in total trying to fix it. I told the merc specialist guy ages ago to stick a camera in the dpf and see, but at that time he said he couldn’t get one in there, but then a few months later he could after I had spent like £900 on it changing sensors and maps. After all that it was dpf issue which I could of solved ages ago had he checked it properly. What was strange was I went to a different merc specialist who read my engine data and said my dpf is running at 7% which he told me was healthy and nothing wrong with my dpf smh

 

[sweeper]

Restricted performance, reduced power, limp mode all the same really, where the ecu sees an issue and limits output rather than reduced engine power caused by a fault the ecu doesn’t recognise, I remember one situation where vehicle was undriveable, diagnostics showed no fault so we couldn’t get authority to repair under warranty, what we need to remember is the ecu is a powerful computer but it won’t always behave in a logical way, like for my R it had the issue a few times with no fault shown or recorded then one time it did! As I found out this particular set of circumstances was known and documented by MB