around 5 weeks ago my engine management light came on whilst driving the still drove perfectly got home took battery off for 30 mins connected it back up the light as stayed off untill today when its come on again whilst driving i took battery off again drove the car too work and back and to the supermarket and its fine the lights stayed off...whats causing it to come on like i say its 5 weeks since it last happend but the car drives perfect ..what i have noticed is its using more fuel could it be the lambda sensor but theres two sensors one on the down pipe which looks difficult to remove and one just after the cat which looks easier????..is this my problem??

the only way to check is to read the codes when the light is illuminated. as it could be any one of the sensors playing up.