i don't know what it is any info will help

 

The light shows that the lambda sensor has detected a fuel/air ratio which is significantly different from standard. Plenty of detail in this article:

http://en.wikipedia.org/wiki/Oxygen_sensor

Mine came on after a brief misfire a couple of weeks ago, it's still there, when I fix the misfire I'll work out how to turn the light off. The car seems OK with it on (apart from the occasional misfire).

There will be a fault code recorded that will help diagnose the problem; I'm sure someone here will know more.

Jason