Of course it is cheating. Would it pass a road side emissions test? no.

So its not legal then is it?

The conditions of an MOT emissions test are only that way as its the only easy practical way to do it. There is no mobile rig they can plug in a do a test drive, nor would they want to have to do that.

So deliberately fudging the ECU to change its map for an MoT test so it seems to be a low emissions vehicle is blatently wrong.

Funny how the law seems to agree by giving them a likely massive fine.