Defender engine immobiliser light

[lynas13]

Hi guys, thought i may as well check here before trying the local garage. I was driving the defender yesterday and the engine immobilisation light came on out of the blue. Got home and had a read of the manual but there seems to be nothing about a constant engine immobilisation light coming on, it only talks about a flashing one. The car starts fine so its not actually immobilised and turning the allarm on and off hasnt sorted it. Anyone has this problem?

Thanks
Jack