Td5 warning light

hugs need some help , 2005 td5 defender , been running fine this morning after a couple of short runs went to start turned key and got nothing , no click , red engine warning light was on turned it off left for few seconds tried again started no prob and no warning light on dash ,been fine all day , what is the red engine symbol a warning of any one know ? Thanks all

Its normally a problem with the fob, it is also the immobiliser chip so worth putting a new battery in it (following the handbook instructions). Also having too much stuff on your key ring can shield it