W204 DPF Issues

[pembssurf]

So after calling out Mercedes (Actually RAC who turned up) roadside assist for my 2013 plate c250 CDI with only 40k on the clock -“after it went into limp home mode the RAC scanner revealed the following.(screenshot below)! Looks like a classic blocked DPF. Fill level is currently 87% and the RAC guy jumped in the car with me for a blast on the dual carriageway and tried to initiate a forced regen but the car wouldn’t have it. Apparently exhaust temp needs to be in excess of 600 degrees but on live data was not getting past 290 degrees despite holding it at 3k revs on the dual carriageway. So 87% full DPF with error on exhaust back pressure sensor 2 ... what are my options? Currently car is out of limp home mode and just took for 60 mile blast on the M4 doing revs the whole way with a bottle of Wynn’s DPF cleaner in half a tank of diesel.

Worth me buying a icarsoft device? Would I be able to force a regen with this or simply just be able to see the door level?

All advice greatly recieved!

Also what the hell are the other codes about haha.

 

[grober]

P0471 could also be the result of a faulty differential pressure sensor which measures the pressure drop across the DPF as an indication its blocked or not. That or the dual pipework that leads to it is blocked/ damaged . This is quite common fault. Did your RAC man discount that possibility ? Do you do a lot of short journeys with little change of a regen?

 

[pembssurf]

P0471 could also be the result of a faulty differential pressure sensor which measures the pressure drop across the DPF as an indication its blocked or not. That or the dual pipework that leads to it is blocked/ damaged . This is quite common fault. Did your RAC man discount that possibility ? Do you do a lot of short journeys with little change of a regen?

After doing a bit of reading you may well be right. I think it may well be an actual sensor failure which is preventing the regen from happening. The car is used for 18 mile 50-60mph A road return journey every day with the odd short run and odd very long run so fairly suspicious for a DPF to be clogged at 42k miles with that kind of running I’d imagine?

 

[grober]

That daily routine should be OK I would have thought, but who knows. This might be of interest?
https://www.motor-talk.de/forum/aktion/Attachment.html?attachmentId=757224

 

[classiccarzone]

Lets read things properly. Your dpf "fill level" will read up to 108% (roughly) every few hundred miles. (280 to 310)

This does not mean that your DPF is "clogged up" and it did not regen for the mechanic as it did not need to and in any event it had a faulty sensor, so the necessary signals were not been sent.

There is no need to bring your car up to 3000 revs for a regen. Doing this will cause more harm than good; much more harm than good.
Plus you are creating more soot in the DPF.

What blocks your DPF is soot, measured in grammes. What eventually kills your DPF is ash; the residue of forced and other regen's, other than passive regens.
Your car will do its passive regens at 50mph and with the temp at 80c. You will not even know it is doing it.
An example of my W204 OM651 220 cdi:

Fill level fills steadily to just over 100%. 280 to 310 miles; Ash goes to 3g. Car then reduces the fill to zero and the soot to zero and the cycle starts all over again. My ash is at zero.
I do mixed driving and always use dipetane in the fuel.
I think that if you look at Grobers link you will see that they state that the regen will not be noticed.

Also if your car commences a regen you do not have to keep racing it around the M25. If you stop mid way it will resume the next time the temperature and speed reaches the ideal level.

Have a look as grober suggested, also keep in mind that some of these engines have a habit of breaking inlet manifold bolts leading to air leaks. This can throw a P0471 code and also prevent the car from regenerating in any form.

 

[pembssurf]

Quick update, car went in garage today and the replaced sensor but it’s still throwing up abnormal readings so it’s staying in there till they can sort it. Sounds expensive but barring a blocked DPF my Tier 1 warranty should hopefully cover it.

 

[pembssurf]

Well 2 days in the main stealers and they still can’t figure out the problem.

Personally I think it may be the wiring harness to said sensor as Iv seen a service bulletin posted somewhere on this board about it.

 

[pembssurf]

Ok quick update to close. As suspected it was both sensor for exhaust back pressure and the associated harness/connectors that had to be replaced to fix the fault and show the correct values.

 

[pembssurf]

Just to add my Tier 1 warranty has now saved me just over £5000 in 3 separate repair costs since June this year. Best £565 iv ever spent. No quibbles, no paperwork, no phone calls and guaranteed courtesy car after 24 hours.