UK Auto Repair Questions?
Hello! My name is Gary.Welcome to JustAnswer.I'm reviewing your question now, and will post back with a reply shortly.
I'd be looking at the oil feed pipe for blockage.
Sounds like the turbo is about to fail again.
Poor oil change history can contribute to this in turbo engines.
Can you describe the noise a bit more, you say sounds like a siren?
Squealing, air pressure leak etc?
I wouldn't associate any noise with DPF regeneration.
I would contact your recent repairer.
Noises happen from abnormalities, they don't fix themselves.
I have replaced a few turbos, and none have given me grief.
Yours is either overspeeding, or there is a boost leak.
Without hearing it for myself, it is difficult to say.
Hope this helps.
Do you need any further help?
I hope my advice has been of assistance to you.