The engine check light has been on in my truck ever since it went to the LPG service centre when I was out of the country. It still runs although in fairness it may have defaulted to rich setting I don't know. That was a minimum of 10,000 kms ago.
When it travels a bit further and gets to 100,000 I will take it to a local workshop, recommended by friends, and get the timing belt changed and the accessory belt, have the oil changed, new spark plugs and they said they will also check the fault code. Which may or may not be the O2 sensor.
You need to find a good local repair shop. Simply ask them to check the code.