DPF / Boost Pressure Sensor issues...

[A1Dan75]

Been having some gorwing niggling issues with my '07 170 TDI, not sure how linked they may be. Wondering if any of you experts can give any advice... a magical fix for the lot would be much appreciated!

In the last six weeks or so, the DPF regen warning has come on three or four times. On each occasion ten or twenty minutes on the motorway has got the light off, but this seems too regular to me? Had never had it before in the previous 18 months of ownership.

Around the same time, I started to occasionally notice a slight niggle with power delivery. Was only just noticeable and only intermitently, but there seemed to be a bit of a stutter / lack of power, like a slight misfire.

Now, on xmas eve, a couple of days after getting the injector recall letter and booking it in for new year, the injectors went while on holiday in the Yorkshire Dales. Fortunately managed to restart after initial failure, got it back to in-laws house in limp mode, after which it refused to statr again and got a tow to the nearest VW dealer, 40 miles away! Anyway, long and short was they replaced all four under warranty.

However, since then, I ahve once again noticed a slight but definite intermitent issue with power delivery, and in the last week I've had twp "Engine Fault" warnings resulting in limp mode. Both times restarting the car sorted it out. I popped into my mechanic to check the fault and it was the Boost Pressure Sensor - "Implausible Reading" or smoething similarly amusing.

Yesterday I got my 3rd DPF regen warning.

So, are the DPF regen / Boost Pressure Sensor fault / slight misfire likely to be linked?

And is it anything to do with the injector replacement, or is that just coincidence? DPF warnings and misfire were both happening prior to injector replacement, but the Boost Pressure Sensor fault has only happened since.... as you can tell I'm fairly confused by it all!

I'm taking it into my mechanic to have a proper root around, but if any of you could offer any guidance from past experience, would be really helpful!

Cheers

Aidan

[dazza291970]

I had issues with DPF warning coming on, along with flashing Glow Plug light and emmissions warnings.
This turned out to be Exhaust Pressure Sensor (G450), fairly easy to replace and about 50 pounds for the part.

This all started after having 3 injectors replaced interestingly (already had the first done!). When I had injectors replaced there was a LOT of smoke for first few hundred yards, not sure if this is normal?

Did your mechanic give you the full fault code?

[A1Dan75]

I didn't get the specific fault code. Did see it on the screen of the VAG gizmo though, and as I say it was something about "Implausible reading" from the BPS.

[Crasher]

We are a bit stuffed without the codes but a faulty DPF exhaust pressure sensor is common and they do need special setting up which I find VCDS does not do very well.

[A1Dan75]

Presumably DPF exhaust pressure sensor is different to boost pressure sensor though... Or is it?

Error definitely mentioned BPS not EPS.

[A1Dan75]

For the user who PMd me, but whose mailbox is now full (or anybody else who wishes to comment!)...

Excuse my total ignorance on the subject, but what does a forced regeneration entail? Is it purely a software issue to persuade the electronics that the DPF is clear, or is it a physical blasting of the DPF?

My mechanic has suggested putting some Forte DPF cleaning additive in prior to a long motorway journey (got one coming up next week) - any thoughts on that?

[Crasher]

A boost pressure sensor (usually called a MAP sensor but VAG call it a "thrust" sensor) and a DPF pressure sensor are different things. A forced regen is carried out using a diagnostic computer system but it must be done with great care, I have seen the lap top show the DPF peaking at around 850 degrees C, right on the edge of what it can take.

[A1Dan75]

So the forced regen is basically using the diagnostic computer to thrash the engine and get extreme heat in the exhaust? Or have I got the wrong end of the stick?

Is it at all normal for the DPF warning to come on again only a week or two after being cleared? I can see how it logically would do, if it clears as soon as you are under the "error" threshold. But that would be daft, as you'd potentially be in a state of constantly getting the error and having to clear for the rest of the cars life.

May also be worth pointing out that over xmas (and hence after the first DPF warning) we did a good long old journey from Derbyshire to the Yorkshire Dales (2 hours mostly doing 60+) and then a run down from Penrith back down to Derbyshire (a good 90 minutes at 80mph on the M6/M61). I would have thought that should keep the DPF clean for a while afterwards?

[manity]

forced regen doesnt thrash the engine it just retimes it so more excess fuel burns in the DPF raising the heat and getting rid of the soot. engine forced regen engine speeds are between 1500 and 2500 revs until the % drops to zero.

[dazza291970]

I was having the warning on maybe once a week, and then twice had emission/glow plug warning along with limp mode which can only be fixed with a forced regeneration I believe.
On VCDS I could see DPF was struggling to get below 16%.

As soon as new sensor fitted and recoded on VCDS the percen dropped withing a couple of mins of driving to about 3% and no warnings since.