Quote:
Originally Posted by Serf27
How would a downstream leak after the O2 sensor affect it to the point that it says 0V?
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My not complete understanding of how exhaust leak effects O2 sensor is like this: The post cat sensors are narrow band sensors. They generate a voltage based on the amount of O2 difference between the air inside the exhaust and the air outside of them, the ambient air. When exhaust leaks especially close to the O2 sensor, the 02 percentage around the area outside of the sensor is reduced. Then the sensor incorrectly would report exhaust air has too much O2 in it, because it compares it to now a polluted reference.
I have no idea that that would cause the sensor to report as low as 0V though. Probably not.
Just wrote this to tell that the exhaust leak and 02 sensor interaction is not like intake vacuum leak and MAF sensor interaction.
The exhaust connection where the flanges rust and eventually leak is after the post cat 02 sensors, but it is very close to them, and so can pollute their air around them.