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dopiaza
19-06-2019, 01:21 AM
Hi,


Hoping to get some help from the gurus here! Picked up a 2010 TT TDI S Line Speical Editon a few days back and took a bit of a punt as it has the DPF, glow plug (flashing) and engine management lights on. It's now in permanent limp mode.


Through a lot of googling I've learnt a huge amount about DPFs in the last few days - my experience is pretty much all from the pre DPF MK4 & Mk5 Golf TDIs so similar but different if you know what I mean.


Anyway, to keep my first post to a reasonable length I've got a few questions about DPFs having tried pretty much all I can to get the car to do a regen. I have access to VCDS and a lot of experience in using it on earlier TDIs.


So... My question is about the differential pressure sensor. I have taken a look at the values and the thing that really stands out is that they are definitely high (100mbar at idle) but seems to flatline at 326 mbar - never above when driving (in limp mode remember), even though it should clearly be reading higher as the curve suddenly flat lines at this value while the engine is still at fairly low revs/load. Is this the highest it can read? Or maybe it's a limitation of VCDS? reading sits at 0 mbar with engine stopped.


I've read a lot about these sensors failing (mine is the 'made in Malaysia' one), part number 076906051A. Only fault shown in engine module is:


009315 - Diesel Particle Filter
P2463 - 000 - Excessive Soot Accumulation - MIL ON
Freeze Frame:
Fault Status: 11100000
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 167943 km
Time Indication: 0
Date: 2019.06.12
Time: 00:23:35


Freeze Frame:
RPM: 851 /min
Speed: 0.0 km/h
Pressure: 79 mbar
Hex Value: 0xFF01
Temperature: 96.0°C
(no units): 40.8
Mileage: 1080 km


So should I be throwing a new sensor it it before anything else, or is the sensor correctly reporting a seriously blocked DPF?


Thanks!

dopiaza
19-06-2019, 07:22 PM
Well OK, for anyone reading this, 326mbar does seem to be the maximum that VCDS can read from the DPF pressure differential sensor - as I discovered having bought a new sensor. Looks like the DPF is truly blocked so will look at some mechanical cleaning methods, hopefully without removing the damn thing!

Crasher
20-06-2019, 04:19 PM
On the car cleaning is useless. Take it off and send it to DPF Clean Team, they have recovered some awful ones for us.

dopiaza
20-06-2019, 07:41 PM
I'm quite surprised (and pleased) to say that I seem to have fixed it!

Was looking at Terraclean and similar companies that wanted between £200 and £400 to diagnose and clean the DPF, then looked at getting the JLM DPF clean kit at around £200 but saw this on ebay...

2 X MANNOL DPF CLEANER X2 FOAM CLEANER | eBay (https://www.ebay.co.uk/itm/2-X-MANNOL-DPF-CLEANER-X2-FOAM-CLEANER/153405144593)

Mannol DPF cleaner part number 9694. 2x400ml cans for £16.99 - in case the ebay link expires

Squirted a can full in through the temp sensor hole that faces the engine block - virtually cold engine, had been run for a minute or so at idle. Took 5 mins or so of short blasts to get it in without it backing up and moved the pipe around as much as possible while spraying. Left it 10 mins and fired her up. Immediately saw idle pressure around 50mbar when it had been 80-110 before. Left it to idle for a few mins then held the revs up for a few mins which created quite a bit of smoke but none of the foam you see on some cleaning videos. Idle pressure dropping all the time down to 40mbar or so.

Took it out for a drive with live VCDS logging and could see the measured soot fall from 47.4 to around 27 over a distance of 10 miles or so. For some reason 'specified' soot stayed around 48. Drove for 30 miles ish hoping it would do something then tried forced regen while driving and standing. No luck with either. Then went through the process to tell the ECU it has a new DPF at which point the soot levels both evened out around 30 and I managed to successfully run a forced regen while driving. Measured soot went right down to zero, with specified soot getting down to around 5. Pressure differential around 10mbar at idle now and staying well under 100 under load.

Finally out of limp mode for the first time since I bought the car and I have to say the 2.0 TDI CR 170 engine is a beauty! Feels like it has considerably more than 170bhp and doesn't actually sound bad (for a diesel).

Time will tell how long lasting the fix is but I'll keep an eye on how it's doing regen wise so I can see any problems arising before they happen.

Next... Haldex pump open circuit.

Fun!