O2 Sensor Voltage higher than possible


#1

The freeze frame data collected from a 2008 Nissan Sentra is showing that the O2 sensor voltage (bank 1, sensor 1) is higher than possible. Specifically, the OBDII showed voltages of 2.822, 2.192, and 2.662 on three different dates. I believe the maximum possible voltage that the O2 sensor can produce is about 1.0 volt. Any idea what is happening here?


#2

@trcunni

“Any idea what is happening here?”

Simple

That bank 1, sensor 1 is almost certainly NOT an oxygen sensor

It is an air/fuel ratio sensor, which operates quite differently from an old school oxygen sensor. And it has much higher voltages, which are supposed to be steady, unlike the fluctuating oxygen sensor signal


#3

Many newer cars use an air/fuel ratio detector in the pre-cat position (upstream), which is more sophisticated than the basic O2 sensor.
They can put out higher voltages, typically up to 5V.


#4

I wonder if OP’s scanner is incorrectly showing a pid which says “O2SB1S1”

It should actually show “AFSB1S1” or something to that effect

In any case, the pid should show AF, not O2

I’ll go off-topic . . . oxygen sensors are still alive and well in newer cars. But their only duty seems to be to monitor the cat efficiency.

So OP’s car has an upstream AF sensor, but the downstream sensor is still an O2 sensor


#5

Thanks. Yes, my scanner is showing O2S B1S1 (V) which led me to incorrectly assume this was an O2 sensor. Thanks for letting me know that it is really an AF sensor!


#6

@trcunni

Your scanner . . . is it showing a steady signal for that sensor?