I know I have a bad o2 sensor, and I have one on order. The wierd thing that I just noticed today is that my instentaneous l/100 km is 8.5-11.5 (around 23-27mpg) , usually it is 0. would this have anything to do with the o2 sensor, or are there any other things that i can check while waiting for the o2 sensor. i love tinkering on the car :P