2019 Dispatch P2448 secondary Air Injection System High Air Flow Bank 1

[Sliff2502]

Hi, I hope you can help. I am getting the above error code on my 2019 Dispatch and the mechanic has already changed two hoses on the system which has not corrected the fault and he is at a bit of a loss now. The warning lights come on after about half an hour of motorway driving in 6th gear. I can drive around town all day long and it never comes on, any ideas? Also I have a trip to France next week am I going to damage the engine too much?

Thanks

Dan