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O2 Sensor Strange Live Data

2011 Toyota Camry LE 2.5L L4 (4 Cylinder)


So I finally got a scanner. I’ve been doing some live readings.

My car has an exhause manifold cat. And 2 sensors. Bank 1 Sensor 1 is an Air Fuel Ratio Sensor, usually hovers around 3.1 to 3.2 volts with current hovering between -0.082mA to -0.055mA. This sensor is new.

Bank 1 Sensor 2 is an Oxygen Sensor. The voltage always starts out at 0 Volts until I start driving it around then it will hit something like 0.045V and slowly increase.

Once im on the highway, while accelerating, this Oxygen sensor will hover around 0.800V.

Now when I take my foot off the gas pedal, the voltage of that Oxygen Sensor drops to 0 Volts. The fuel system also switches to open loop at the same time when that happens.

The fuel system always switches to open loop when I take my foot off the gas pedal. The Oxygen Sensor drops to 0 volts but not every single time. I have a feeling the Oxygen Sensor is staring to fail but I have no codes to prove it.

What do you think is going on with my Bank 1 Sensor 2?

-Thank you all

Me thinks you are just looking for trouble . No codes , vehicle runs OK ? , fuel mileage has not decreased ? , might be a good idea to relax and just wait until you have a problem.


@VOLVO-V70 You are exactly right! I am looking for trouble. This is entirely on purpose. I am a firm believer in preventative maintenance. I just want to know if the sensor is being accurate or on its last leg and keep the car up to spec.

You probably know this, but I’ll ask anyway. Are you scanning when car is at operating temperature?

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This is normal. When the engine speed is above 1400 RPM and the throttle is closed, the fuel injectors are switched off, the oxygen level in the exhaust goes up and the oxygen sensor voltage goes down.


@tcmichnorth Yes

@Nevada_545 Thank you!! So the sensor flatlining to 0.000V is ok right?

You are describing perfectly normal operation of a downstream oxygen sensor.

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@asemaster Thank you!!

For my own knowledge: about it going to open loop during deceleration. Is that normal?

Yes, the input from the upstream air/fuel sensor is invalid when there is no fuel burned and a high oxygen level in the exhaust.

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It goes open loop because the computer is taking control of the air/fuel ratio from sensor 1 and using an internal preplanned program that tells the fuel injectors to shut off until idle conditions are met. Then the computer controls the amount of air via the IAC and sensor 1 takes control of fuel delivery again.

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