W221 OM642 2012 - DPF Ash Content Zero!

[mbmb123]

Got a diesel W221 with 50k miles. Using a iCarsoft V2 shows unfeasible values:

- Ash Content: 0g
- Last regen kilometer: 67250

My understanding of DPF operation is that it will trap soot, which will gradually block the filter.
The degree of blockage is measured by front/rear pressure differential.
When sufficiently blocked, and other conditions are met (engine temp, exhaust temp, enough fuel in tank!) a regen takes place.

A regen involves injecting fuel into the DPF to burn the soot. The DPF temperature will significantly increase during the process. How long it takes on a MB I don't know, on my SAAB 10-15 mins.

After the regen the soot has been transformed to ash, which remains in the DPF.

So, for a car with 50k miles I don't believe the ash content is 0 grams, and I don't believe the last regen milage figure.

Is the iCarsoft reading the data wrong? Has someone tampered with the DPF?

 

[zipdip]

Welcome, I think you will find that the 67250 is around 41,000 miles so it would seem you cars last regen was around 8000 miles ago,it is a nice low mileage W221 they are about,people do buy these cars and do very little driving,odd I grant you, but maybe you could give some other reasons why you think things are not right,I know that if I put a Icarsoft on a W221 after I bought it and just got these values I would be pleased.

 

[D-18]

I have an iCarsoft LR V2 for my Jaguar and I download various readings from the car at the end of each month just to monitor any trends and hopefully identify any issues which may be progressing.

Up to now, the car has been just fine so I'm not about to 'fix' anything. Although the iCarsoft unit is quite good, it's not a dealer level reader and I take all of its readings with a large pinch of salt. For example, I've had it report positive values for 'Oil quality fuel dilution factor' right after an oil change (either done by me or the dealer). Clearly, this cannot be correct as the oil is brand new! It has also reported completely incorrect readings from the TPMS sensors and incorrect (far too long) intervals between DPF regenerations.

I monitor the 'DPF soot concentration' readings too. My car is 5 years old with 30K miles on the clock. I noted a reading of 15.69g/m³ at the start of this year and this is now sitting at 23.14g/m³. The figures have varied up and down throughout the year as the car does its own thing with regeneration. I've never been conscious of the car regenerating, it just does it.

So the iCarsoft may give an indication of any issues, but I wouldn't really put any great faith in what it is telling me - I bought it so that I could tell when I should get the car checked on 'proper' equipment (this hasn't been required yet!).

It might be worth having your car checked by a proper dealer level code reader to clarify the situation. If someone has tampered with / removed the DPF, the tailpipes will be sooty rather than clean.

 

[mbmb123]

Wow, wan't expecting such early replies.
I took a pic of the message, I had it wrong
"Driving distance since last successful particulate filter regeneration: 69593 mile"

The ICarsoft has an option to switch between metric and imperial, but I don't think it always gets it right. There will be some bugs in their software.
In this case, if it meant km rather than miles, and it meant Odometer reading and NOT driving distance that would be 43,500 miles.
Maybe that was the last regen, I'm suspicious because my SAAB regens more often.

Regarding the low ash content, I've seen youtube vids:

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showing some ash content, zero doesn't seem right for 50k miles.

I started looking at the DPF because a fault was thrown last week.
15FD00 state: historic, the lower limit value of component B28/8(Differential pressure sensor(DPF) ) was dropped below/not reached.

The result was that it would only use gears 1 2 and 3, and limited the acceleration. I guess this was limp mode, but nothing showed on the dashboard.
After parking up for 1 hour and returning to the car it ran OK.

 

[D-18]

The problem for DIY spanner twiddlers (like me) is that these codes can be misleading. At best I feel they can give you an indication of where to start looking, but they're no substitute for an experienced mechanic who can fully interpret the symptoms.

For example, many years ago I had a Vauxhall Cavalier automatic which repeatedly threw up a gearbox fault. The source of the problem was actually a faulty alternator which was sometimes putting a 'spike' in the electrical system and triggering the gearbox fault. This took several trips to the garage and the expertise of a very experienced mechanic to finally diagnose correctly. The car was charging properly and there was no obvious indication that the issue lay with the alternator.

My point being that DIY code readers are fine, but I tend to use mine simply to confirm when I should take the car to a good dealer / indy for diagnosis. As one of my friends used to say 'buying the same toolkit as the chief mechanic doesn't make you the chief mechanic'.

The iCarsoft unit has confirmed there is a fault with the car, I'd now consult a dealer / indy to identify what is the underlying cause.