did it come on and stay on or on and off did it go into limp mod or was it still driving fine reason I'm asking was in my Astra on Saturday night and the light came on a couple of times for about 3 mins at a time while driving @ 80 mph I noticed that the car temperature @ dropped to well below normal(as it was abit cold) just above the blue on the gauge and I have am in the thinking it had something to do with the cold temp sensor telling the brain to run richer(if that makes any sense)so lamba was picking up the wrong signs come to this conclusion by when it happened the next time I pulled up and let the car tick over until it reached nornal temp ie 1/2 way on the gauge and it didn't happen again

IT COULD BE DIFFERENT ON YOURS THOU!