Vauxhall Cora - Automatic 2018 - ! "Engine Power is Reduced"

Hi, the above warning has happened twice now - first time I took it down a local garage and the connected up the computer and cleared the fault but could not find any other info.

The second time it happened I was was after I went over a pot-hole - so I wonder if the jolt had activated a warning of some sort.

The first time, after a few hours the car seemed to reset and the error had gone, but this time it's still there.

The main problem when the warning is there is that it hardly gets out of 1st / 2nd gear and as it's auto I can't do much else - not a good thing if I'm on the motorway.

Is there anything I should ask the vauxhall garage to look at specifically, as I'm sure they'll just do a test drive and say they can't replicate the fault.

Thanks