Hello and welcome Lee.
Engine management lights and wonderfully vague things as they tell you something, but also tell you nothing.
To get to the bottom of what it is indicating, the exact code needs to be read off. The exhaust leak is quite possibly the culprit. There is a thread somewhere about OBD thingies. If you're handy enough with a smartphone and get a bluetooth plugin thingie, then you should be able to read the fault code with that (and clear it afterwards). I've never tried this by the way, but then my general spanner fare has been much older vehicles from the pre-cat era. Other OBD diagnostic choices are available (such as a laptop/software/cable)