The noise, researching the error code and asking the guys down at @Jez @ H-Dev aka Horsham Developments.
Unfortunately I don't have the space/tools to do an exhaust leak check but was pretty sure after listening out for the noise and the background reading.
If you've got axle stands / ramp / non powered car then I'm sure you could get underneath and shine a light at the gaskets. I don't have the picture to hand but mine were blown sideways and it was clear as water that the gaskets were faulty. Hope that helps?