It's a non-dedicated (the battery light shows up in the same square when the key is on and the engine off) orange square light about 1" square that is in the instrument cluster and there are absolutely no switches for it. I think it has something to do with cycling the key and a certain number...
Your Lambda sensor ( also called oxygen or O2 sensor ) looks like the top of a spark plug with wires coming off the top of it/them (there are 2 or 3 of these sensors) they are fit into the exhaust system of the car up near the engine area and 1 may be behind the muffler but probably not on this...