Originally posted by hondata
An oxygen sensor produces an electric voltage from the different levels of oxygen present in the air and the exhaust gas. If the mixture is rich then the exhaust gas will contain very little oxygen. The oxygen sensor will therefore product a voltage output, which the ECU senses and determines that the fuel mixture is rich. Conversely if the fuel mixture is lean then the exhaust gas will contain higher levels of oxygen, which produces a lower voltage output. The normal range of the oxygen sensor output signal is about 0.2V to 1.2V It should be noted that most stock oxygen sensors are designed to be particularly sensitive around the stoichiometric air/fuel ratio.
