Madami pwedeng causes nyan kasi. One is, obviously and that is why the casa says it often, bad fuel. Do you check the filter element that was removed? Makikita mo naman kung madumi talaga. Another is water in the fuel, which is again bad fuel. Water in the filter housing will trigger the sensor and cause a cel. 1st thing to do is change gas stations, go to a newer one or one that is not in a flood prone area. If you already switched gas station and you still find water in the fuel then there is also the possibility that the water may not be from the gas station, it could be due to a bad fuel filler cap gasket, or a small hole in your tank or filler tube that allows humid air to go in at night. Try keeping your fuel tank mostly full as a full tank will not let much humid air in and therefore less condensation. And if you notice that there is less water after this exercise (which may take several months) then you might want to consider having your fuel tank checked.

Another factor you need to consider is the filtering ability of the filter element. What is the micron rating? 10 uM, 5 uM, 2 uM? The finer the element the faster it gets clogged, BUT it is just doing its job as it was designed. So check mo yung micron rating ng filter, both types, then compare. Take into consideration that a 10 uM filter may take a long time before it needs replacement but it lets everything 9uM and below to pass and wear your pump and injectors. A 2 uM filter gets clogged fast but it offers the best protection for your engine.