I know it goes on the o2 sensor but which wire on an 99 up mustang?
i would have to say that's like 60% true. Is it going to come straight out and say your A/F ratio is 12.7:1 or something like that, no. But if you learn how to read it correctly, it'll give you more or less an approximate reading. If you're looking for something that gives you an exact number, then you'll need a wideband 02 sensor which usually costs around $400.steedav6builder said:i wanted to get an autometer a/f guage too. is it true that they are not acurate?