denny your real close but no cigar. the o2 sensor is a battery that works with two dissimilar fluids that fluid is o2 the air outsie the o2 sensor is 21% o2 diference between the outside samole and the inside sample generates current that the computer reads in milivolts up to 1 tenth of a volt the more 02 on the inside sample the lower the voltage thats why if you have a missfire the 02 goes out the exaust unburned the computer sees low voltage and sets a lean mixture code .....ted