If you let it run that low, you'll drag all sorts of shis from the bottom of the tank into the engine and then the engine is to try and burnt that off.
The light prob wont go off itself, you could try and dis-connect the battery and leave it for a while and then re-connect it but your car might need radio codes etc.
If that doesnt work bring it to a gargage and they will knock it out, you could also have two much air in the system as you ran out and this affected the lambda probe reading (same light on most cars).
Petrol Lawnmowers are hardly the same as a diesel car/jeep engine.