Intermittent Fault (Limp Mode) C220 CDI

[Paco42]

Good morning.

New member here, so go easy : ).

I bought a 2010 C220 CDI back in October last year at 84000 miles. All servicing done, etc. However, it's started to go into Limp Mode intermittently. I've taken it into the MB Specialist I use and they put it on a STAR Diagnostic yesterday. The only fault found was to do with an 'Exhaust Pressure Sensor', which it's booked in for next week to get sorted.

Apologies if this has been discussed; I looked on the sticky posts, but couldn't find an answer as it's intermittent. There was some damage to the wiring loom under the engine cover, but this was repaired yesterday.

Anyways, looking forward to joining the forum! Has anyone experienced this kind of issue before?

Many thanks,

Neil

 

[zipdip]

Welcome aboard,what was the PO number for the fault,good to see you are using a indy to sort it,what starts off as the sensor can soon become DPF related and forced regens,when owners take the car to a ordinary garage,keep us posted as to what goes on.

 

[OneForTheRoad]

Back pressure sensor fault is as common as the cold.

 

[Paco42]

Welcome aboard,what was the PO number for the fault,good to see you are using a indy to sort it,what starts off as the sensor can soon become DPF related and forced regens,when owners take the car to a ordinary garage,keep us posted as to what goes on.

Thanks for the reply! Can't see a PO number for the fault, but diagnostic also says, as well as the exhaust back pressure fault, it also had two earth faults and 2 glowplug faults. These have been cleared and the wires repaired as mentioned, but the fault has returned today : (

Sorry for my ignorance, but what do 'DPF' and 'Forced regens' stand for?

Hope this doesn't turn into a big problem!

 

[zipdip]

Well the DPF stands for diesel particle system it is designed to trap soot particles and so lower emissions,the car is supposed to burn these off when they start to build up,it is possible to notice when you drive the car because the revs will go up and the system will get very hot,now if the car does not regen itself then it can be forced too,but as it is the indy is saying it is the sensor lets hope it cures the problem,has the garage changed the sensor and you are saying the fault has returned or that the glow plug fault has returned..

 

[Paco42]

Well the DPF stands for diesel particle system it is designed to trap soot particles and so lower emissions,the car is supposed to burn these off when they start to build up,it is possible to notice when you drive the car because the revs will go up and the system will get very hot,now if the car does not regen itself then it can be forced too,but as it is the indy is saying it is the sensor lets hope it cures the problem,has the garage changed the sensor and you are saying the fault has returned or that the glow plug fault has returned..

Thanks for explaining that. Very interesting. The garage isn't due to change the sensor until next Wednesday. I'm sure they STAR it again and see if any problems have returned.

UPDATE: I've just driven home and it's now showing an orange Engine Management Light on the dash. Additionally, if I'm sat stationary in Drive, say at lights, the car has been shaking like hell, like it's on the verge of stalling. Very strange for an automatic.

Anyone had this??

 

[Paco42]

Back pressure sensor fault is as common as the cold.

Thanks. Can that sensor be a cause for putting it into Limp Mode?

 

[OneForTheRoad]

Thanks. Can that sensor be a cause for putting it into Limp Mode?

Very much so.

 

[OneForTheRoad]

Very much so.

Shaking could be a dpf regen interrupt

 

[Paco42]

Very much so.

Cheers. I'm having 'One for the Road' now after the lottery of getting home.

 

[OneForTheRoad]

Cheers. I'm having 'One for the Road' now after the lottery of getting home.

If it is that sensor , and your handy . Its a 5 minute job. Sensor i think is about ,£50 at mb

 

[Paco42]

If it is that sensor , and your handy . Its a 5 minute job. Sensor i think is about ,£50 at mb

Not that handy tbh! I'll stick with the Specialists.

 

[Paco42]

Shaking could be a dpf regen interrupt

Is that an easy fix?

 

[OneForTheRoad]

Is that an easy fix?

Possibly, don't interrupt a dpf regen . Trouble is we never know its doing one. Every 300 miles i read somewhere???

Id run dpf cleaner with every tank of fuel , premium fuels like esso ,shell etc at that mileage is when things begin to clog up. Also give it a redline now and again to blow out some crap.

 

[MrGreedy]

If you do a search on this forum against my username and dpf and/or regen, there's loads of threads with useful background information on the DPF, its function and problems.
Shaking at idle isn't one I've heard of. The regen over fuels the car so that fuel gets into the DPF, and this burns off soot that is captured by the filter. The only way to interrupt a regen is turn the car off, which on a 2010 car you definitely shouldn't if you can detect it is doing a regen.

You could have a catalytic convertor breaking up or a clogged DPF. Both of these would cause exhaust back pressure.
Of course, it might not be that as well. A very knowledgeable independent Merc specialist is the way to go. Unfortunately I don't have any recommendations for Cheshire area.

If the forum search function claims that "DPF" has too few characters for a search, you can specifically search the forum google using:
"keyword" and "site://forums.mbclub.co.uk"

Where keyword is replaced with the search terms you are looking for
Don't include any of the " "
You can use this for any website with the "site://" prefix to force Google to only show results from that site

 

[Paco42]

Possibly, don't interrupt a dpf regen . Trouble is we never know its doing one. Every 300 miles i read somewhere???

Id run dpf cleaner with every tank of fuel , premium fuels like esso ,shell etc at that mileage is when things begin to clog up. Also give it a redline now and again to blow out some crap.

Great stuff. I’ll pick up some DPF cleaner before the next refill. The Engine Management light has no gone off! What the heck!

 

[Paco42]

If you do a search on this forum against my username and dpf and/or regen, there's loads of threads with useful background information on the DPF, its function and problems.
Shaking at idle isn't one I've heard of. The regen over fuels the car so that fuel gets into the DPF, and this burns off soot that is captured by the filter. The only way to interrupt a regen is turn the car off, which on a 2010 car you definitely shouldn't if you can detect it is doing a regen.

You could have a catalytic convertor breaking up or a clogged DPF. Both of these would cause exhaust back pressure.
Of course, it might not be that as well. A very knowledgeable independent Merc specialist is the way to go. Unfortunately I don't have any recommendations for Cheshire area.

If the forum search function claims that "DPF" has too few characters for a search, you can specifically search the forum google using:
"keyword" and "site://forums.mbclub.co.uk"

Where keyword is replaced with the search terms you are looking for
Don't include any of the " "
You can use this for any website with the "site://" prefix to force Google to only show results from that site

Thank you so much for this. Never heard of this before, so interested to know what it’s all about.

 

[SamwiseC250]

Great stuff. I’ll pick up some DPF cleaner before the next refill. The Engine Management light has no gone off! What the heck!

I can't tell if mine is trying to do a regen, but I wish my engine light would just go off, seems like its in limp mode as its got a lot less power than normal, doesn't seem to be misfiring and it's not smoking at all, I think it's dpf related but like I said it doesn't seem to be trying to regen, help

 

[CarFan79]

I can't tell if mine is trying to do a regen, but I wish my engine light would just go off, seems like its in limp mode as its got a lot less power than normal, doesn't seem to be misfiring and it's not smoking at all, I think it's dpf related but like I said it doesn't seem to be trying to regen, help

If your engine light is on it will not even try to regen as it knows there is a fault. On a side note, it will not regen when the low fuel light is on either.