Unlike a standard O2 sensor which switches between rich and lean, a wide-band sensor has an output voltage which is directly proportional to the oxygen content of the exhaust.

Narrowband oxygen sensor voltage output. The output is heavily dependent on sensor temperature and highly non-linear, making these sensors unsuitable for delivering a true AFR reading.

Narrowband oxygen sensor voltage output. The output is heavily dependent on sensor temperature and highly non-linear, making these sensors unsuitable for delivering a true AFR reading.