<P> The average level of the sensor is near to 450 mV . Since catalytic coverters need a cycling a / f ratio the oxygen sensor is not allowed to hold a fixed voltage, the ECU controls the engine by providing the mixture between lean (and rich) in such a sufficiently fast manner by means of shorter (or longer) time of signal to injectors, so the average level becomes as stated about 450 mV . </P> <P> A wide - band sensor, on the other hand, has a very linear output, 0--5 V, and requires a much hotter running temperature . </P> <P> If the purpose of the air--fuel ratio meter is to detect also an existing or possible problem with the sensor above of checking the general mixture and performance, a narrow band air - fuel ratio meter is sufficient . </P> <P> In high - performance tuning applications, the wide - band system is desirable . </P>

Where is the air fuel ratio sensor located