W204 C220 CDI, DPF problems
Discussion
I’ve owned this car for nearly five years, it’s never gone wrong - however, it has now.
It’s lacking low down power and the engine management light is on. I’ve put a Snap-on Solus ultra scanner on it and I have a code P246397 - which is ‘The soot content of the diesel particulate filter is not ok’
I ordered a new DPF pressure switch and fitted, just in case it was that. The fault persists. I’ve now also removed the DPF and washed all the black crap out of it (there was loads), refitted it, almost 100% sure I solved it. Nope.
On the scanner data, it’s recording soot levels of 400% in the DPF, even after cleaning. I’ve taken it out for a good run after all of these works and it’s still lacking power and the fault code P246397 won’t clear for long.
I’ve even driven it briefly without the DPF even fitted (turbo noise
) and it’s still saying high soot levels - this is with the pressure switch pipes dangling in the wind. I’ve also tried refitted the old pressure switch.
I’m now acid bathing the DPF, thinking that maybe it is still blocked, but then why after clearing the code and driven without, does it still see a high level. Am I missing something?
Thanks in advance.
It’s lacking low down power and the engine management light is on. I’ve put a Snap-on Solus ultra scanner on it and I have a code P246397 - which is ‘The soot content of the diesel particulate filter is not ok’
I ordered a new DPF pressure switch and fitted, just in case it was that. The fault persists. I’ve now also removed the DPF and washed all the black crap out of it (there was loads), refitted it, almost 100% sure I solved it. Nope.
On the scanner data, it’s recording soot levels of 400% in the DPF, even after cleaning. I’ve taken it out for a good run after all of these works and it’s still lacking power and the fault code P246397 won’t clear for long.
I’ve even driven it briefly without the DPF even fitted (turbo noise
) and it’s still saying high soot levels - this is with the pressure switch pipes dangling in the wind. I’ve also tried refitted the old pressure switch. I’m now acid bathing the DPF, thinking that maybe it is still blocked, but then why after clearing the code and driven without, does it still see a high level. Am I missing something?
Thanks in advance.
Have you had a look on the two main UK Merc forums? I've seen this before, but don't recall a definite solution. I have seen calibration suggested, but others say it's a red herring.
Standard thing with any Merc issue is to get it on their diagnostic tool, StarDiagnose, at a Merc indie.
Standard thing with any Merc issue is to get it on their diagnostic tool, StarDiagnose, at a Merc indie.
Edited by Sheepshanks on Saturday 1st September 21:57
Just had this same fault on my sons car. 400%
Fault was DPF soot accumulation.
I took it to Merc for a dynamic burn. £300 well spent as some of the fannies wanting to look at it and back flush it with foam magic formula whatever were shysters.
Go to Merc. Have the car back next day fault free. Job jobbed.
Fault was DPF soot accumulation.
I took it to Merc for a dynamic burn. £300 well spent as some of the fannies wanting to look at it and back flush it with foam magic formula whatever were shysters.
Go to Merc. Have the car back next day fault free. Job jobbed.
Whats the mileage and what year is the car?
Merc had a few issues with wiring loom connectors at the beginning of the 651 engine, causing high readings when actually it wasn't [DPF].
DPF's do have a shelf life. Soot content is a the ECU's best guess as there is no physical way of measuring 'soot' content in a DPF. It's linear calculation taken over the life of the vehicle. You should also be able to read the estimated Ash content reading. Ash is a bi product and unable to be burnt off during the regen, the only way to rid of the ash within the filter is something like a terraclean, or new DPF. I've no exp with terraclean, or how effective it is.
As someone pointed out above, after a new DPF has been fitted, whether new or cleaned the Engine CU needs to be reset to know it's now had a new DPF fitted to restart calcs.
What are your pressure readings on live data, at certain RPM's? That should tell you more than you need to know at the moment.
Merc had a few issues with wiring loom connectors at the beginning of the 651 engine, causing high readings when actually it wasn't [DPF].
DPF's do have a shelf life. Soot content is a the ECU's best guess as there is no physical way of measuring 'soot' content in a DPF. It's linear calculation taken over the life of the vehicle. You should also be able to read the estimated Ash content reading. Ash is a bi product and unable to be burnt off during the regen, the only way to rid of the ash within the filter is something like a terraclean, or new DPF. I've no exp with terraclean, or how effective it is.
As someone pointed out above, after a new DPF has been fitted, whether new or cleaned the Engine CU needs to be reset to know it's now had a new DPF fitted to restart calcs.
What are your pressure readings on live data, at certain RPM's? That should tell you more than you need to know at the moment.
Classy6 said:
Whats the mileage and what year is the car?
Merc had a few issues with wiring loom connectors at the beginning of the 651 engine, causing high readings when actually it wasn't [DPF].
DPF's do have a shelf life. Soot content is a the ECU's best guess as there is no physical way of measuring 'soot' content in a DPF. It's linear calculation taken over the life of the vehicle. You should also be able to read the estimated Ash content reading. Ash is a bi product and unable to be burnt off during the regen, the only way to rid of the ash within the filter is something like a terraclean, or new DPF. I've no exp with terraclean, or how effective it is.
As someone pointed out above, after a new DPF has been fitted, whether new or cleaned the Engine CU needs to be reset to know it's now had a new DPF fitted to restart calcs.
What are your pressure readings on live data, at certain RPM's? That should tell you more than you need to know at the moment.
It’s 2010 and 137,000 miles. Do you know how to reset the ECU?Merc had a few issues with wiring loom connectors at the beginning of the 651 engine, causing high readings when actually it wasn't [DPF].
DPF's do have a shelf life. Soot content is a the ECU's best guess as there is no physical way of measuring 'soot' content in a DPF. It's linear calculation taken over the life of the vehicle. You should also be able to read the estimated Ash content reading. Ash is a bi product and unable to be burnt off during the regen, the only way to rid of the ash within the filter is something like a terraclean, or new DPF. I've no exp with terraclean, or how effective it is.
As someone pointed out above, after a new DPF has been fitted, whether new or cleaned the Engine CU needs to be reset to know it's now had a new DPF fitted to restart calcs.
What are your pressure readings on live data, at certain RPM's? That should tell you more than you need to know at the moment.
There's a couple of posters in this thread that might be able to advise: https://forums.mbclub.co.uk/threads/w204-c250-dpf-...
It might just be that your diagnostic tool, which is a goodun by the look of it, doesn't have the required functionality to tell the car the dpf is now clean?
That's where finding a local independent with the star tool comes in. Wouldn't have thought it'd cost much to get it hooked up??
Good luck with it.
That's where finding a local independent with the star tool comes in. Wouldn't have thought it'd cost much to get it hooked up??
Good luck with it.
Sheepshanks said:
There's a couple of posters in this thread that might be able to advise: https://forums.mbclub.co.uk/threads/w204-c250-dpf-...
Seen that thanks. I’ve already started a thread on there, but no response as of yet 
dave_s13 said:
It might just be that your diagnostic tool, which is a goodun by the look of it, doesn't have the required functionality to tell the car the dpf is now clean?
That's where finding a local independent with the star tool comes in. Wouldn't have thought it'd cost much to get it hooked up??
Good luck with it.
I hope it’s that simple, the car is supposed to be going to it’s new owner this week. That's where finding a local independent with the star tool comes in. Wouldn't have thought it'd cost much to get it hooked up??
Good luck with it.
peaktorque said:
Sheepshanks said:
There's a couple of posters in this thread that might be able to advise: https://forums.mbclub.co.uk/threads/w204-c250-dpf-...
Seen that thanks. I’ve already started a thread on there, but no response as of yet Your machine is not capable of resetting the DPF setting. You need something more sophisticated than a snap-on (which despite the price is not the best).
Pressure differential is very low, and the DPS looks like it's working OK, (assuming you were blipping the throttle) so the unit is clean, it just needs telling that it is.
100% convinced it's this, and I do it for a living. (so I must know what I'm talking about eh?)
Pressure differential is very low, and the DPS looks like it's working OK, (assuming you were blipping the throttle) so the unit is clean, it just needs telling that it is.
100% convinced it's this, and I do it for a living. (so I must know what I'm talking about eh?)
Sheepshanks said:
peaktorque said:
Sheepshanks said:
There's a couple of posters in this thread that might be able to advise: https://forums.mbclub.co.uk/threads/w204-c250-dpf-...
Seen that thanks. I’ve already started a thread on there, but no response as of yet 
bearman68 said:
Your machine is not capable of resetting the DPF setting. You need something more sophisticated than a snap-on (which despite the price is not the best).
Pressure differential is very low, and the DPS looks like it's working OK, (assuming you were blipping the throttle) so the unit is clean, it just needs telling that it is.
100% convinced it's this, and I do it for a living. (so I must know what I'm talking about eh?)
I’ve borrowed the machine from my uncle and it’s taken me a while to suss it out!Pressure differential is very low, and the DPS looks like it's working OK, (assuming you were blipping the throttle) so the unit is clean, it just needs telling that it is.
100% convinced it's this, and I do it for a living. (so I must know what I'm talking about eh?)
Thanks
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