Toyota Avensis "Malfunction Indicator Lamp"

[AM]

This warning light came on this morning on the way to work, I checked the book and it says to take the car to a Toyota dealer as soon as possible. I'm going to book it into the garage later today but wondered if anyone can give me an idea of what it might be, I'm of to France in a few weeks and the last thing I want is to be worrying about the car conking out !

There was no loss of performance or any sign that anything's wrong at all apart from this light. The car has just gone over 100000 miles so I'm hoping it's just a service reminder....