Having driven like Miss Daisy for a few hundred miles, I almost got caught out by a cross-country B road dash. The OBC was showing a range of 50 miles, but that went down to 5 miles in no time at all. I filled up before the range got to zero. The car continued to drive as perfectly as ever, but the EML came on the next morning.
I phoned my local indie specialist (VGS - can't recommend them enough) who said it would probably go out by itself, but offered to check it out if I popped in. They were as right as always - when I got in the car the next day to drive over to them - no EML!