O2 Sensors carry a wealth of information, i've been doing a lot of services lately and part of the service is a scan, i'm taking notes on the fuel burn readings i'm getting, and they are not good.
There's nothing wrong with the vehicles i service, a lot of mechanics would replace the O2 sensor, but getting readings of O2 sensor code may not be a faulty sensor, in most cases it's the un-burnt fuel that saturates the sensor that throws the check engine light, when the fuel evaporates the sensor gets proper readings and the light goes off.
Changing your fuel filter will not solve the problem, it will improve it, and you should replace fuel filters with every fuel problem and when it's time. So how do you solve this issue? add some octane boost to the tank, fill the tank with premium fuel and that's it.
To avoid it from happening again, don't use that bowser for a good two weeks, servos have to change filters regularly, it's the law, however it's not the filters that are at fault, it's the bottom of the barrel quality of crude that we import, 7% of it according to my readings do not burn, that may seem a little but it's a huge difference to an engines performance, economy and most of all life.
If you look at the cost of fuel, we all look to the cheaper fuel, but premium fuel is the standard fuel or gas as the USA, our standard drops to 91% burn, and even premium fuel does not burn completely. The smart thing to do is use premium fuel at the same bowser every time you fill up, just a few % more burn will give you better performance, better economy and better milage and your engine will last longer.
when the combustion occurs in the engine, not all that fuel is burnt, most goes out the exhaust, but some blows by the rings and down the sump, this carbon affects the oil, shortening the life of the oil, that unburnt fuel goes throughout your engine and dries it out, more friction, more fuel is needed to keep up with the drivers demand, resulting in poor performance more services, more money in the long run.
I recommend in Australia to pay a few more cents for the premium, it works out roughly the same in comparison to 91 or 95.
I hope this helps if your car is running poor