2017 1.5 DCI Power loss

[CakeDealer]

Hello all!
This is my first time posting but I've been using this forum for some time to fix odd things on my Qashqai.

The most recent issues has got me abit stuck and hoping one of you fine qashqai owners can shed some light..

So recently my 2017 1.5 DCI qashqai (Diesel, around 75,000miles) has suffered quite substantial power loss all of a sudden and often won't get above 50mph, certainly not uphill however will still rev high.
I have not noticed any smoke out of the exhaust or any whining from the engine.

I have a OBD reader which gave me a few fault codes:

P0101 - Mass or Volume air flow circuit range/performance problem

P0380 - Glow plug /Heater circuit A

P1498 - Powertrain
Google isn't 100% sure on this one, different sites say different things but I think it's Exhaust Gas Recirculation (EGR) valve fault

So I set to work ticking them off starting with the easiest..

It's not going to be the glow plug circuit as the car starts fine, it is over due new glow plugs but I'll get to that once I've sorted this..

Mass Air Flow sensor (MAF)
Located and disconnected the MAF, it was a little dirty so cleaned it with some electrical contact cleaner spray and made sure the filament was intact.
Whilst doing this I found the air filter extremely clogged too so changed this out for a new one.
To make sure, we have another Qashqai 1.5DCI 2014 in the family with no faults so swapped the MAF sensor to check it was working. Seemed to work fine.

Cleared fault code and went for a drive.. same issues.
MAF sensor fault also still comes up.

Next,
EGR Valve,
Located it and removed it, it was clogged with carbon so potentially not able to open and close the valve properly?
So I cleaned it with some engine degreaser and got rid of all the carbon build up and replaced.

Whilst doing this, I noticed alot of oil on the engine cover and around the Turbo boost pipe to the intercooler.
I took off the engine cover to expose the tops of the glow plugs - no oil there.
Only place it could have come from was the join of the turbo boost pipe itself where it spring clips to the turbo.
This is worrying me slightly,
Inside the pipe there isn't any carbon build up but there is a layer of wet oil surrounding the inside of the pipe in both directions.
As I mentioned before though there is no smoke out of the exhaust when driving or whining from the engine/turbo that I can hear which are the usual signs for turbo failure?
Should there be this much oil on the inside of the pipe or is the turbo leaking oil? How do I fix this? Is this causing the loss of power?

The only other thing I have thought of is the DPF is clogged which if the EGR was caked in carbon maybe the DPF will be also? I have bought some fuel additive DPF cleaner to put in and see if it makes any difference before I go taking the DPF off to flush. Only down side of this is for it to work properly I have to get the revs up to burn off the soot after adding... But if I do that and the turbo is leaking oil and fails, that's a much bigger/expensive job.

Any help/advice would be greatly appreciated!

[liam_bee]

Can't help massively on the power but does sound like the dpf is clogged, but you'd usually you get a dpf excessive pressure error before you feel it, could be an injector failing (I've felt those before the car says) or a boost leak- my turbo has been leaking oil for about 50k miles and still boosts ok (just have to keep oil topped up!),
Does your reader do live diagnostics? You'd see the boost level on that

[Vinche]

Hi Cake Dealer,
I sent you a PM. I have all your sympthom.. did you solve it? How?
Thanks in advance,
Vincenzo

[Vinche]

I solved by replacing turbo intake tube