As dontpannic says. The light will reoccor after a time if it's not fixed.

I have a full milltek sytem with sportscat on my car. When I have the standard map the light appears. If I reset it with my faultreader it dissapear, but will reoccur after 1-2 weeks.

When I use the pumaspeed map, it's no light. Hope it will pass MOT though, since I don't have my old exhaust any longer haha.