How to reset engine malfunction light on Nissan Almera 2002?

My engine malfunction light came on yesterday and also my car felt a little juddery and sluggish, got my uncle whose a mechanic to look over it and the oil was pretty low after he topped it up it's been running lovely but the light is still on!! Is there anyway of resetting it so the light goes off with out paying nissan £35 to do it for me?! I've seen a few posts on here about the timing belt but he checked that over for me too and that is fine no problem. Hoping to sell my car soon and won't be able to get the price I want with this light on!!