2.0 TDI Underbosting problems - Many codes thrown, help please

I'll cut to the chase. Bought a 2011 TDI Sportswagen that has a few issues. It drove 75 miles home fine at 70-75 mph but without boost. And would decline speeds up hill. Was in limp mode I guess? (Averaged 48 mpg btw)

Problems: It has no boost, or very little to say the least. These are the codes it's thrown.

P0401 - Exhaust gas recirculation flow insufficient detected
P240F - EGR Slow response
P2008 - Intake manifold runner control circuit/open Bank 1
P0299 - Turbo underboost
P2015 - Intake manifold runner position sensor/switch circuit range/performance Bank 1

I've checked the simple stuff. IC pipes and vacuum lines and all seem fine. I'm off to buy a vacuum pump to test the turbo vane control piece, but upon sucking vacuum with my mouth it appears to be functioning fine.

Any help greatly appreciated guys and girls. Thank you

How many miles? Any service history of DPF or EGR replacement?

160,000 miles and no history relating to the DPF or EGR, that I'm aware of. After giving the car a check, everything seems pretty original. No bolts/lines messed around with.

It's probably still covered by the extended emissions warranty. Look for a sticker under the hood indicating when the emissions fix was applied.

turbobrick240 said:

It's probably still covered by the extended emissions warranty. Look for a sticker under the hood indicating when the emissions fix was applied.

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This ^^^^ would be my first move, also.

The fix was not done on this Vehicle. I called VW to schedule a fix but I don't know if they'll warranty anything that needs to be fixed prior to getting the fix done? Any insight on this?

Can't I just take it back after the fix and say I just had these issues come up?

They won't "fix" a car lit up with codes. I'd take it to a good VW mechanic rather than the dealer. Good luck!

turbobrick240 said:

They won't "fix" a car lit up with codes. I'd take it to a good VW mechanic rather than the dealer. Good luck!

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Are you 100% sure on this? Because I told them it had a check engine light and they didn't seem concerned.

Anyway I'd still like to fix it properly before taking it to VW in 3 weeks time anyway. So if anyone has any insight on what the problem could be I'd love to hear from you

The dpf is almost certainly cracked internally. This causes soot to clog the egr filter and thus the egr codes. The turbo may also be shot. Whoever the owner was that passed up the VW money and fix screwed up badly. I think it's going to be very expensive. Perhaps more than the car is worth. Sorry

Well I'm thinking of removing that section and running the car to see if it boost as it should. Is that something that can be done?

I've read the "fix" consisted of replacing the DPF anyway, so would it not be best to just let VW go ahead and do this if this is the case?

Update - thinking of removing the EGR filter and checking out the condition of it/cleaning it if necessary as this can put the car in limp mode.

Another update - I just remembered on my 75 mile drive home the temp never read in the middle at 190, and I recall the my prior TDI would always stick at the middle regardless of outside temp. And I'm in FL where it was around 70.

SO, maybe it's not getting up to temp and if that doesn't happen, it wont enter regen to clear the DPF? Is this right?

Beau168 said:

Another update - I just remembered on my 75 mile drive home the temp never read in the middle at 190, and I recall the my prior TDI would always stick at the middle regardless of outside temp. And I'm in FL where it was around 70.

SO, maybe it's not getting up to temp and if that doesn't happen, it wont enter regen to clear the DPF? Is this right?

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@ 70* outside temp. you should read straight up @ 190* right after hitting the freeway, let alone a 75 mile drive. The engine has to hit normal operating temps among other things to Rengen. For starters you may want to look into a hung open thermostat? I would imagine not going into closed loop would set your other codes.

Well those codes were read on a generic code reader. I have a OBD11 on the way to read more specific codes so I should be able to see if the thermostat is bad through that right?

Although I'm thinking if it was the thermostat that has caused the regen not to work, it's probably been like this a long time now and caused the EGR filter to clog/dpf bad.

I've read you read how "full" the DPF is. Anyone know if I can do this with the OBD11, or do I need VCDS?

Beau168 said:

Well those codes were read on a generic code reader. I have a OBD11 on the way to read more specific codes so I should be able to see if the thermostat is bad through that right?
Although I'm thinking if it was the thermostat that has caused the regen not to work, it's probably been like this a long time now and caused the EGR filter to clog/dpf bad.
I've read you read how "full" the DPF is. Anyone know if I can do this with the OBD11, or do I need VCDS?

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Ive only used a generic OBDII reader on mine. I had a faulty glow plug setting the CEL. It only pulled the codes 1 time even tho I cleared it a half dozen times before the repair. The way i confirmed both thermostat and heater core efficentcy is use an automotive thermometer in the center vent. Watch the temp gauge as the car warms up to 190* (thermo closed to open status) The heater temps should closely mirror gauge temps.

The Polar will read DPF load, when its in a regenerating and all sorts of info. According to VW the DPF replacement is @ 200 ml ash lload.I asked the VW tech to check the DPF ash load when the car was in for the CPO covered repair.

So little update on this.

I've checked the N-75 valve thing. It appears to work just fine. I also checked the actuator rod itself and it moves up and down fine when applying vacuum. Not stiff and smooth operating. I checked on lines and all appear fine, check valve works.

I checked boost levels actual vs specified at idle revving the engine to 2500rpm and the boost hardly increases and does not meet specified. It is as though the turbo is being choked. There are no apparent boost leaks and it's not exactly boosting enough to even show signs of leaking anyway.

If the vanes work, what else can choke the turbo like this? Upon manually operating the vanes I can hear as the turbo opens/closes. I checked DPF Levels and it doesn't appear near MAX values. I noticed the MAF may be reading a little off. Can a bad MAF cause the turbo to behave like this? I unplugged it and it didn't appear to make any difference, but it DID throw a code when I unplugged it. Is the turbo just bad?

You mentioned earlier never reaching full operating temp. Have you got full operating temp yet?

No I haven't had the needle dead center yet. But would this have any effect on the turbo not boosting?