it would be interesting to find out which codes it can read. Although I'm not wishing a fault on you so that you can find out....
That was part of my bad Monday afternoon! I pulled the fuse to turn the EM light off, but I'm hoping there's a stored code. Having had the light in May as well, I thought it was about time to buy a reader!
The light came back on at Dunkirk ferry port yesterday evening on the way back to blighty

Luckily, my new code reader was waiting at my destination address (my parents) that I'd ordered 10 days ago. Really easy to use, only needed a cursory glance at the manual. Anyway the code was P1181, which is to do with long term fuel/air mix too lean. A bit of googling showed that it it most likely to be an air leak somewhere in the intake system, or at least a hose on the inlet side somewhere. It also mentions the possibility of a MAF sensor problem. Embarrassingly stupid question, but never had any problems like this before, I'm assuming it's the big alloy thingie just behind the drivers side headlight?

I've cleared it for now, be interesting to see if it reappears.
Interestingly, this is the same code that was thrown in May when we got to the UK, and was cleared at the time. It seems to have taken 5 months to reappear so perhaps not a big deal? I'm wondering if it's something to do with the long fast thrash across Europe, although to be fair I was only pottering the other day when it popped up.