New owner help? Reduced engine power

Hi I'm new to the volvo life and I bought a 2016 d4 v60 2L diesel. The test drive was fine however a few days later I had a reduced engine power warning however it seems to drive perfectly fine the garage is got it from said it was some pipe that needed replacing from when they plugged it in but the error message still comes up its on 150k miles if that helps?

I'm suppost to be driving to naples in 2 months despite it driving fine I'm obv worried. Is this going be a costly repair