Replaced turbo, now DPF filter/low bank codes/CEL. What did I do wrong?

[Tanjenttt]

Hi,
2015 CRUA TDI 2.0 in a Golf Sportwagen. 99,000 miles, manual shift 6 speed. Mods done by VW, dealer purchased in California around 2018, as I recall.
Inlet turbo fan ate itself, no boost, had to drive about 15 miles like that. Hard to say how that happened... No other damage to the turbo--shaft good, vvt good, housing good...
Took it apart and replaced the turbo with new...
After start up, seemed good. On the way home the DEF hose to the DPF came loose, CEL light came on; I guess I did not seat it properly. Reattached it about a mile and a half later, it spilled a bunch of def fluid on the back of the engine, etc. Code came up for low bank cat 1; with the hose reattached the code cleared about thirty miles later.
CEL light stayed off for about 75 miles, then came back on, now getting low bank code and a big ass DPF replacement warning on the dash...
Is there something I should check about my work before I go ahead and do major service? Tailpipe is pretty clean...
I am new to diesels but know my way around engines...
Thank you

 

[TurboABA]

Let's see code\scan results.

 

[Tanjenttt]

Hi,
All I have is an OBDII scanner. There are two codes for the same thing: P0420 Catalytic converter below efficiency threshold, bank 1.
CEL is on and th4e dash says check the Diesel Particulate filter, refer to owners manual. That is not terribly helpful, so I was hoping that someone with some experience with turbo replacement or DEF line disconnections while driving could point me at some things to look at...
Thank you

 

[TurboABA]

Not having a proper bidirectional diagnostic scanner\tool will only cause you or anyone else to load very expensive parts into the cannon. You can't work on\maintain\own modern CR diesels and still rely on $30 Amazon diagnostic dongles. Spend $200, get a tool, see what's going on, or take it to a shop and surrender your wallet.

 

[GBaugh]

Turbo failures often result in damage to the dpf if the failed turbo allows oil into the exhaust. Oil and soot in the dpf can restrict the dpf air flow and prevent soot from being burnt off with regeneration.

For clarity, DEF is not sent to the DPF catalyst. Def is injected into the SCR catalyst which is downstream of the dpf. I suspect that your DEF line disconnection incident is unrelated to the dpf catalyst efficiency fault. The P0420 fault is indicating a problem with the dpf catalyst and not your SCR DEF catalyst. Are you sure the hose that came disconnected is a DEF hose and not a dpf differential psi sensing hose? If a dpf diff psi sensing hose became disconnected that would make more sense with an efficiency problem being detected.

 

[Francobenz]

@Tanjenttt
Before going too far, does your car still have dieselgate warranty? https://www.vw.com/en/emissions.html
Turbo and DPF are both included if still the case

 

[Tanjenttt]

@GBaugh: Thank you, that is very helpful. The turbo failure was pretty strange in that the bearings were fine and only the inlet impeller was damaged. In my experience, bearing failure will often send massive amounts of oil into the exhaust; in this case not so. It seems I got lucky and no shrapnel from the impeller fan made its way through the engine... Better to be lucky than good I reckon... There does not seem to be a code for doing a bonehead thing like putting the EGT sensors in in the wrong order... (Read on)
Car is apparently not under warranty.
I carefully looked at the problem and found that I had swapped two of the EGT sensors. I swapped them back and went for a long drive to get the regen going, instead of forcing a regen. Problem seems to be completely solved.
For reference: The EGT sensor that is nearest the turbo has a grey lead and a black plug, I believe it is usually referred to as sensor 1. This one is right below what looks like an o2 sensor, and you will probably have to remove the o2 sensor to properly get to it. The EGT on top of the shiny aluminum can that is attached to the DPF has a black lead and a red/brown plug. This is the one that is easy to get to. The other two EGT sensors would be hard to mix up...
If you want your car to freak out, swap these two sensors.
Regarding scanners: I bought an Ancel HD430 scanner for a little over $200. Not having a pc laptop, this seemed like a good option. It speaks VW and I am happy with the purchase. As someone with pretty extensive mechanical experience, it is more helpful to have comments that suggest directions to go than demands to buy a scanner and upload files...

A further question: The dpf was added as part of the diesel gate recall correct? So it is likely my car with 99k on it had about 50k on the dpf if I got the car with 40k miles on it from the dealer, right? So if I am lucky I can expect another 80k before facing this issue again, barring more boneheaded moves on my part?

Thank you

 

[TurboABA]

It seems I got lucky and no shrapnel from the impeller fan made its way through the engine

So you're suggesting it simply vanished?

There does not seem to be a code for doing a bonehead thing like putting the EGT sensors in in the wrong order...

This is why live data and knowing how to use whatever diag tool you have is important.... one would monitor parameters to see what doesn't make sense.

A further question: The dpf was added as part of the diesel gate recall correct?

Not necessarily. Obtain your service records and find out what was done when the AEM was performed.

 

[GBaugh]

Thanks for sharing that valuable tip about the EGT sensor identification. Good job with catching your mistake! Reminds me of NOx sensor identification. Often NOx sensors will have a gray or black lead that needs to go in a certain position. Ford powerstrokes use a "blue in back" NOx sensor and a different color upstream.
Regarding your question about the Dieselgate add-on aftertreatment, I would have thought the DPF was standard equipment from the factory. I thought the Dieselgate fiasco was more of a software correction, but maybe I'm wrong. I'd be curious to see what other people say about that.