2013 C250d (OM651)- the dreaded DPF issues...

[Pauld1000]

Hi,

I am hoping for some advice!

I drive an 80 mile round trip each day for work, mix of A roads and dual carriageway, so am confident the car would be able to regen on its own normally.

I had a P244a7 code come up a few months ago, and replaced the DPF sensor with a Bosch one. This seemed to fix it for a few days, then it came back intermittently.

Fast forward and I bought the Icarsoft Pro to try and regen it, and the above code has stopped occurring, but now the car is in limp mode constantly, with a code of P246309 'Soot content of the DPF is not ok, there is a mechanical fault'. I've put a new Mercedes DPF sensor on, no change, stripped out and cleaned the DPF, no change, stripped out the EGR cooler, and checked the EGR valve isn't blocked (blackened but not sticking). checked vacuum operation of the valve with a mityvac, and this also works.

The diagnostics are still showing the DPF at 359% and wont allow a forced regen. I have tried resetting adaptations, (mainly has a comms failure), and managed to get it to 0.3 briefly, then it jumped back to 350+%. Also managed to get it to read 185% briefly, started the forced regen and went for a drive but aborted as it was showing a message of 'the test has not yet been started', showing DPF again at 358 (and rising slightly through the drive).

With the live data, I took it out earlier, and did notice a couple of possibly odd readings (although I am not sure what different sensors 'should' read. Readings were:
B60 Exhaust Back pressure I had 3.68Bar (in limp mode) at one point.
B19/9 temp sensor upstream of DPF - 166°C
Air Mass 1063mg/Hub
B28/8 DPF diff press sensor - 0.02bar
B11/4 Coolant temp sensor - 95°C
B19/9 temp sensor upstream of DPF - 306°C
Engine speed - 2698.5rpm
Injection quantity 16.89mg/Hub
Fill level of DPF - 358%
Soot Content - 10g
Ash content - 0g
total distance at last correction of Ash content - 160534km
Y27/9 EGR actuator - 50%

I have also noticed that the Y27/9 Exhaust gas recirculation actuator seems to always sit on or very near to 50% at idle? sometimes goes up to 85% initially then drops down. Physically checking the actuator rod to the valve, this seems to be in one position engine off, and the far opposite engine on?
I'm kind of getting fed up of trying to fault find to be honest and was hoping the above might allow someone with more knowledge to point me in the right direction! I am fine stripping and rebuilding, but not at figuring out what I need to take apart!

Anyone have any advice on what to try next?

Thanks in advance

Paul

 

[onefortheroad]

When I had this issue I changed the dpf sensor and ran the dpf section on icarsoft , the scanner runs checks first to see if a regen is possible. This seemed to adapt the new sensor to read current values and not values of the old sensor, apparently the car doesn't know you've changed it ?? Another thing to try is remove the exhaust pressure sensor ,don't lose the washer !! Start the engine and see what live data reads . If its stuck on the same readings when its in the engine , then its knackered and needs a new one. Normal readings are 980 to 1020 ... unsure what icarsoft uses to measure , think its mb not psi . Maybe change the metric /imperial setting in set up. Good luck.

 

[Kev555]

DPF diff pressure sensor shows Dpf isn't blocked if I'm right as pressure difference seems ok or sensor is faulty. some of the sensors aren't working stopping it from regenerating is my guess. Some of the components that control the Regen are blocking the icarsoft from completing a regen. I didn't catch which sensor you changed, not familiar with your car but theres possibly three sensors on it. 2 temp sensors and one pressure sensor at least. Did you change the pressure sensor as well? Is there a mistype in your first post? should one of them temp sensors not be downstream Paul?

 

[Pauld1000]

Well I took it out again today, ran the test fill level of DPF which came up as 0.37, then straight into the regen drive, and it still wont regen. I am pretty sure the back pressure sensor is ok as it sits at 1bar (atmos) with the ignition on. I am curious though if the EGR is still causing an issue as this (Y27/9 EGR actuator - 50%) seems to be a constant number?

 

[Kev555]

Could be the EGR stopping it as well although I'm not familiar of how they effect the DPF when faulty?

 

[Pauld1000]

DPF diff pressure sensor shows Dpf isn't blocked if I'm right as pressure difference seems ok or sensor is faulty. some of the sensors aren't working stopping it from regenerating is my guess. Some of the components that control the Regen are blocking the icarsoft from completing a regen. I didn't catch which sensor you changed, not familiar with your car but theres possibly three sensors on it. 2 temp sensors and one pressure sensor at least. Did you change the pressure sensor as well? Is there a mistype in your first post? should one of them temp sensors not be downstream Paul?

No typo - the Icarsoft states both as temp sensors, although there is a typo, these should read:
B19/9 temp sensor upstream of DPF - 166°C
B19/11 temp sensor upstream of DPF - 306°C
I'm pretty sure the diff press sensor is working correctly as it reads 0.0, and occasionally flickers up or down very slightly (by maybe 0.01 either way), which like you say suggests the DPF isn't blocked (which I am sure of given I have removed and cleaned it, and you can see light through it).

 

[Pauld1000]

That seems to be the only number that stands out to me as not looking right - wouldn't it be 100% open (or closed) on start up, not at 50% even with the ignition on, engine not running...

 

[Kev555]

Somebody will be along to advise on whether the EGR performance can affect the ability to regen(I deleted my EGR later along with a remap). My own EGR was throwing up fault codes but never affected a regen. Temp sensors dont look right at a second glance, they shouldn't be running with so much of a temp difference from memory. I will try to take a look at mine tomorrow to confirm if I get her up to temp(only 3 mile to work)

 

[Kev555]

Your temp sensors do look out of kilter Paul. I had a look at mine this morn when I got to work to refresh my memory and the two sensors where within 20-30 degrees of each other with coolant at 44 degrees. Unless your sensors are further apart on exhaust system than mine is only way I could explain temp difference on your car

 

[Pauld1000]

Thanks for that - I have booked it in to a local DPF specialist who will do a diagnostics and full assessment for £90 so fingers crossed they will figure out what the problem is!

 

[Steve@Avantgarde]

You can't just replace the DPF pressure sensor. You need to check and update the software then Carry out a regeneration whilst driving. If you dont have online Xentry or a pass through diagnostics system, you won't be able to cure your problem.

 

[Pauld1000]

Well it came back from the garage and they diagnosed a faulty Thermostat (reading at 65°C) which would explain it not regenerating, and stated the DPF is actually damaged and has to be deleted/repaired, depending on future use. Apparently the pressure drop across the DPF was too low as it was passing completely due to the damage, and so the total opposite of blocked!

I don't want to do the deletion so have ordered a new thermostat and DPF, and will hopefully be able to reset the adaptations when I have replaced the parts...

 

[Gazwould]

Ah , the flawed system.. many , many victims.