Interesting results from DPF star check

haggettd

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Interesting to me and any other owners with DPFs

Follow up to previous thread regarding DPF Star check.

Well.
The chaps ran a star test and came up with the following results:-

Code 2621-002 Ash content of diesel particulate filter TOO HIGH

Fault counter 3
Kilometer reading 8698 -- 11420
Engine speed 1460 -- 1540
Last regeneration - -- -
Ash content of DPF - -- -
Resistor - -- -
Current Injected quantity 0.00 -- 19.20
Info Dev Status 12.0 -- 12.0
Exhaust temp down stream of TWC 385 -- 285
Exhaust gas volume flow rate 180 -- 100 m3/h
Differential pressure 89.5 -- 44.5 hPa
Resistor 11.2 -- 9.6

So, I don't know how these figures relate to a DPF that's new or within limits - maybe someone could explain some of the above.

The bottom line though is that the DPF's over the ash limit so I have requested that it should be replaced under warranty considering I have had the car only 4 weeks and it was purchased from MB direct with a 12month warranty.

Am I correct that a forced regen would only lower soot levels and not Ash content?

Do you think there is a chance they would have any argument against this on the grounds that it's a 'consumable item'? I hope not cos it's £650 plus labour.

This news backs up my suspicions that the economy is lower than it should be and that I believe that it's trying its best to regenerate every 70 miles or so.

I have not bettered 40.2 mpg (calculated tank to tank) driving like miss Marple on my 140 mile daily 65mph motorway commute. I would expect 45mpg at least.

Hopefully with a new, clear DPF this should improve somewhat. I'll keep you posted.

It does highlight the importance of using the correct spec Low Ash oil when you have a DPF fitted. I suspect that the incorrect oil may have been used in the past (Castrol SLXII Longlife) - can't seem to find what MB spec that is - Anyone know?

The car is a 220CDi 05 with 69000 miles Auto Estate BTW.

I'll update this thread with further news.......thanks for reading.
 

124coupe

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2621-2 - ash above limt - can also be caused by a faulty pressure differential sensor (i.e. lying about the back pressure from the "ash" in the DPF).....either way a good catch while in warranty!
 

124coupe

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It would be great to see the same diag after a good hard Italian - a chance to see if it works!
 
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haggettd

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I wonder though if a faulty differential sensor would have its own error code!

I would hate to risk an italian tune up in case it works and brings the ash into the "it's fine now sir" zone.;)

On that, wouldn't said tune up simply create a tiny bit more ash after burning the soot out?
 

LYNALL

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Had a retrofit one of these apart on a 7.5 ton truck the other day and i washed all the muck out with a steam cleaner, not very high tech but seemed to work, was suprised by the lack of soot in the silencer assy.

As its a retrofit it cannot regenerate itself hence the reqd stripdown, stripped because pressure said its blocked.

Have heard of poeple doing similiar on peugeots with great success and also improved mpg afterwards.

Iirc there is something they can do with the star to get it back to spec.


Lynall
 
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haggettd

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I believe the star regen is mainly used on cars that are driven at low speeds around town cos they can't regen themselves. The engine and exhaust doesn't get hot enough so it has to be done via star.

Funny enough, I discussed this with the technician who did the check and he said it was extremely difficult to get set up to do a 'Star burn'.
You need a password from Mercedes now to enable this function in star whereas before, it could be done with no problem.

He said that the process was deemed a fire hazard as the exhaust gets literally red hot.

I think my problem is due to the car being serviced (By Mercedes) with the wrong engine oil (non low ash) and it's simply that that's clogged it up.

I want a new DPF under warranty for a fresh start, and I'll be a bit of a nuisance if they try and refuse!!
 

124coupe

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I wonder though if a faulty differential sensor would have its own error code!

I would hate to risk an italian tune up in case it works and brings the ash into the "it's fine now sir" zone.;)

On that, wouldn't said tune up simply create a tiny bit more ash after burning the soot out?

It would (it does) if it hard fails but there is a known problem with the sensor output reading that "simulates" high back-pressure from ash loading.

The Italian idea was based on your own admission of driving everywhere very carefully. Not ideal for a DPF-equipped car.

All diesels benefit from a good ratting from time to time!
 
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haggettd

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Points taken.
I note from the service book that the differential sensor and associated hose should be replaced every 8 years.

How is a faulty pressure sensor diagnosed if it can't be detected by the star machine?

I guess if the sensor is a commonly known culprit then Mercedes would know this and advise that it be changed first and have the car re-checked on star to see what the Ash measurement is.

I'll see what they say on Monday.

Thanks for your comments.
 

Alex Crow

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the sensor could be tested with a live data check with the engine not running. the differential pressure would be zero, so any significant deviation in live data from this would point to a failing/failed sensor. this is the kind of guided test star would suggest.
 
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haggettd

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Mercedes Direct have ordered a new DPF for my car. It's to be fitted sometime over the next week.

This pleases me as you can imagine.

I found out also that the incorrect spec oil was used at the cars 18K and 34K services. (MB Stratford -upon-Avon)
They used Castrol SLX Professional Longtec which is not a low ash oil.
Not sure what was originally used. But I would imagine the factory would have put the right stuff in!

So, to answer the question of what happens when you use the wrong oil - your DPF lasts less than 50K.

Should the technician run another star check after fitting to verify all the sensors read correctly?
 

124coupe

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So how are S-on-A making reparations for your inconvenience - next service free?
 
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haggettd

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To be honest 124 I haven't even thought about that yet.
I'm concerned at th moment with making sure MB Balsall do the right thing.
I phoned today and was told that a new DPF has been ordered. They'll arrange to fit it when it arrives. That's a fair result and the only one that'll do considering its past.

I won't tell MB Balsall about the wrong oil yet S on A used - all in good time.

I'll also let MB S on A know of their misdemeanors. They need to get their act together I'd say.

I checked with MB Coventry and asked the chap what parts are actually supplied when a replacement DPF is ordered.
Apparently I should be getting the complete canister which also houses the Oxidation Catalyst as well as the DPF so a complete fresh start.

I'm convinced that my mpg will improve, I cant help feeling that the car feels a bit asphyxiated while I drive it.

Still haven't had any warning lights or errors showing on the display.

Is there any chance of any damage being done with the excessive backpressure anyone?

Thanks everyone for all comments, I'll update when I can.
 
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