help needed with 'heat' dash light

Hi
 
Does anyone know what the 'HEAT' light means - top left of dash pannel on my Jap. Import 1.5i mx3 - it has come on and stays on - car seems fine but I need to get to the bottom of it. Would appreciate your help.
 
 - cheers - Guy

hi ya bud, change the heat sensor probe on the side of cat its easy i fitted a new one on my v6 import today & my heat light has gone out horaay