I honestly can't believe my luck. I bought an Octavia TDI 2013 vRS with 200k. I noticed it was using a litre of oil a week then the P0299 underboost was constantly flashing. Seeing this was constantly happening and there was no signs of oil leaks I took it to a garage.

I was told it was most likely the turbo due to the oil leaking loss of power so £1200 priced to install the turbo.

After nearly 4 weeks I was told today that the new turbo only boosts fully if the 02 sensor is removed. Now I'm being told the DPF must be fully blocked causing back pressure. Soot readings are about %25

I thought this guy had Vcds software but he doesn't. He asked if the DPF was disabled. I told him I have no clue. So now I'm waiting for his mate who's more experienced and has the correct software. I could be looking at a new dpf or have the contents removed.

Anyone that could advise me what else I should be asking or looking for to resolve this would be great.

Im currently renting a car while this is being done and I it's breaking the bank.

Cheers Stu

Edited 31 January31 Jan by StuOctVRS
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Also worth checking out the piston rings as worn piston rings can also cause high oil consumption.

3 hours ago, wiilydog said:

Also worth checking out the piston rings as worn piston rings can also cause high oil consumption.

Yep that has crossed my mind. However it's a back pressure problem now.

To be honest I would've thought plonking a lower milage engine. Would've been a cheaper route

On 31/01/2026 at 18:32, StuOctVRS said:

new turbo only boosts fully if the 02 sensor is removed

This person is tell untruths to you. Its a hack to try and improve performance, but doesn't actually fix the problem.

On 31/01/2026 at 18:32, StuOctVRS said:

DPF must be fully blocked causing back pressure

That is probably right - basically a failed turbo just dumping oil into the exhaust or inlet and will just cause the DPF to clog up. You need a DPF clean. Google DPF clean (don't be tempted to shove chemicals at the problem, it needs to come off and be properly flushed out)

On 31/01/2026 at 18:32, StuOctVRS said:

I thought this guy had Vcds software but he doesn't. He asked if the DPF was disabled

There are many dodgy / ripped off versions of VCDS; anybody who has a version something like 12.2....avoid them as it will brick your ECU. DPF disabling means removing your DPF - illegal and will cause an MOT failure.