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NMB Aug 31st, 2020 21:27

DFP Issues - what’s next...
Hi all,

So after doing a ton of work on the engine, writing it off on a rock, buying it back and repairing the sump, I return to the dreaded “Soot filter full” message.

So what to diagnose next.... here is what has been done:

1) Engine flush
2) Oil change to. Liqui Moli 0/30 low sulphur synthetic oil
3) PCV - valve replacement
4) Breather system clean
5) Oil pan removal, flush and clean
6) Turbo replacement
7) Replaced the resonator box with a resonator pipe
8) Additive for hydraulic valves
9) Additive for valve guides
10) Ceramic coating adaptive
11) No smoke additive
12) DPF pressure sensor replacement
13) DPF pressure pipe work Inspection and clean
14) VIDA Compression test - all in keeping and in tolerance
15) VIDA Injector test - all in keeping and in tolerance
16) VIDA Static regen
17) Clean / decarbonisation of the intake system

After all this I am still getting this dam warning message....

So, when driving the car if I drive carefully and low revs I can prolong the gap between filter full warning. If I put my foot down in first and second gear I can pull up the code immediately.

I have also inspected the charged system many tines as I’m convinced it could be an airleak but I cannot see any leaks. Pipework is all sorted or shows no sign of failure or leakage.

If there is a leak then it must be in the intercooler but there are no signs at all.

Now this is the interesting thing.

After a static region the DPF such value drops to 0. However, it quickly goes up to 20 and then continues up to 26/27 when the Soot filter warning light comes on. Once this activates it slowly counts down and it doesn’t matter whether the car is running or stopped but in 12 minutes the counter would’ve gone back down to about 22. The warning light then goes off and I drive the car again for a short time until the soot filter warning light comes on again.

And here are my thoughts in no particular order:

1) Remove and clean the EGR valve - VIDA shows it is operational but I cannot see huge movement in the valve - how far does it move?
2) Perform a leak off test on the Injectors as they could be taking a dump?
3) replace the intercooler?
4) replace the DPF!

Any thoughts on how I can diagnose this further without spending a ton of cash working out what the problem isn’t?

As always, your help will be greatly appreciated. Hopefully as well with my reporting back this may help others also.


SwissXC90 Sep 1st, 2020 05:39

Smoke test the intake system and look for leaks.

A leak in the charged air system will upset the air/fuel mixture, causing more fuel to be burnt, causing the DPF to fill up quickly

NMB Sep 26th, 2020 08:25

Okay so I have finally got round to working out the next steps with my D5185 bhp. I currently have three Volvo XC 90 and I’m working on them every weekend to keep them going!!

So I have done extensive testing and I have now also replaced the intercooler and I can guarantee there are no boost leaks.

I have set up VIDA and driven the car for 100 miles testing causes for “Soot filter full” message.

1) Boost pressure is constant and in line with required values.
2) The car is automatically regenning and removing the particles recorded. I’ve seen the value go up to 29 and then reduce down to 0 when driving. The regen cycle works well and of course when driving at a constant motorway speed the soot value goes up to 6 or seven and then automatically gets burnt back down to 0.
3) I have already replaced the DPF pressure sensor. When I did so, I blew down the pipes to ensure they were clear and not blocked.
4) If you look at the attached picture you will see the bottom to veins of the intercooler are bent downwards as they have been over pressurised.

It’s my summarisation then that because the car has been burning oil, for a long time prior to me buying probably, the DPF is just knackered.

I hear you say that you need to sort out oil leak/burning of oil in the engine but, in consideration that I have done all the work noted at the start of this post, I am going to assume that the DPF may have been damaged Or just completely blocked up to the point that it cannot turn off enough soot to clear the system.

Lastly, when driving I can avoid the filter message if I drive very slowly and keep the revs down and the boost pressure down. The minute I put my foot down the soot filter warning comes up. This Message comes up with the KPA values from the filter when they hit about 600 Which I believe is far too high and the causation of the low power/limp mode and the soot filter message.

So a new DPF is being delivered today with fixing kit and a new temperature sensor (just in case the old one does not come out of the DPF.) Considering that it’s such an important part of the engine, the cost is only £110 which really surprised me.

I will let you know an update when I drive the car with it fitted. I’m not completely sure that this message will now disappear as the car is still burning some oil. However, with the right oil in the engine (low sulphur ) I hopeful This might resolve the issue for me.

Any comments on the KPA you should be getting when the engine is revved? My number is about 70-140 on Idol / low revs and up to 600 hard revving/engine under load.

NMB Oct 1st, 2020 12:14

So everyone,

After tracing the fault around the car from replacing the near knackered turbo, putting in the correct oil, replacing the PCV and Diff Pressure switch, checking the breething/vacuum system, replacing the near knackered intercooler to then write the car off on a rock (I then had to buy it back off the insurance company and I just installed a new sump for £50 quid + oil) I finally have News!!!!

I replaced the DPF today and instralled a new soot sensor and took it for a run - this is the results...

1) DPF pressure on hard acceleration dropped from 600+ to a normal 45 - 70
2) Car now drives amazingly!
3) Soot build-up was monitored on a 30 mile 40-minute leisurely drive (with occassional hard acceleration) and I parked up with 2.1% soot after the journey - some of this would probably be the engine cleaning itself from the "Asthma" its had for so long.
4) Oil level before I set off was at 75% and when I parked up it was at 77%
5) No smoke at all

So my assumption is that the previous turbo was failing (there was excessive play in the spindle once removed) and this was leaking oil into the dpf slowly killing it. The previous owner possibly put in the incorrect oil also. With the new turbo fitted the problem was solved except that the DPF was too blocked to properly regen. So the back pressure was pushing oil past the turbo seals and into the engine causing more soot in the DPF; I think this makes sense?

The car was smoking, not consistently, and I think it was only smoking as the car was trying to do a forced regen as the DPF was blocked and the smoke was the disel being injected and burning - hence the incostency.
When I tried to do a static regen it said the regen was successful except the Soot% jumped quickly back to 28%+ within a minute of driving or one blip on the accelerator pedal.

Lastly and most importantly, when free revving the engine, on RPM drop off there was a uuuuuugggggrrrrrrrr as the RPM slowed to idle. I think this was the key sign that the backpressure from the blocked DPF was causing the noise - worth listening out for on your cas as its now gone on mine with the DPF replaced.

I hope this helps others I didnt given up!!! Does it mak sense?


V8XCV Oct 1st, 2020 12:30

Good job! DPF issues are a right pain.

Can I ask where to got your DPF from? I think I need to replace mine on the V70.

NMB Oct 1st, 2020 13:07


Originally Posted by V8XCV (Post 2669443)
Good job! DPF issues are a right pain.

Can I ask where to get your DPF from? I think I need to replace mine on the V70.

I bought it on eBay from carpartsinmotion - here are the links:


DPF Fixing kit:

Gas Temprature sensor:

Total cost - £133 + £38 for the temprature sensor - yes thats all!

V8XCV Oct 1st, 2020 14:14

Super, thanks for the links!

NMB Oct 1st, 2020 14:19


Originally Posted by V8XCV (Post 2669462)
Super, thanks for the links!

I thought a DPF would cost hundreds and hundreds! btw

foeism Oct 6th, 2020 09:51

A really informative thread and good to hear a solution at the end!
Nice work!!

mhuttner1 Nov 22nd, 2020 14:07

1.6d DrivE 2009 c30 dpf replacement tips
Hi all,

I have a 72k miles c30 2009 1.6d drive. Car serviced regularly approx every 7k. As far as I am aware it is a wet dpf in this particular model (is this correct) which means dpf should be replaced after 75k miles. Approximately how much would this cost at a dealership. What is the most cost effective way of doing this?
Thanks in advance

Harley Dave Nov 22nd, 2020 18:43

You have posted in the XC90 section of the forum.

You will have more response in the correct section



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