02 sensor readings

Hi, all,

Just trying to understand my O2 sensor readings.

My understanding is that the sensor after the cat (green) should not be this high?

I am assuming the sensor is working. It goes down to zero after load and releasing the throttle.

What does this indicate?

Thanks
Lee



 

I am assuming that this is under load, smallish throttle opening, cruising along the flat. If it is, it’s perhaps a little high but otherwise looks ok.

Your other thread showed graphs at idle and dropping the throttle, they also looked normal. Again sensor 2 looked a little high, but there is variation in everything.

Certainly the graphs suggest that your CAT is working correctly.

Robin

Thanks, Robin. So, a higher voltage on the sensor after the cat is the expected result. I.e. less o2

So, the cat is reducing 02? I am just trying to understand how this indicates the cat is working. I am still quite confused.

To give some background, I am trying to determine whether my front cat is blocked, as the car is behaving similarly to when my rear cat had fallen apart and was blocking the exhaust. Going up hills the car won't rev up unless I drop down to second gear.

Thanks
Lee

Yes, post CAT there should be very little oxygen left. Google Catalytic Converters for more information on the science of how they work. Basically they recombine the oxygen and other gasses with the catalyst to modify the harmful emissions in to something more environmentally friendly.

They don’t emit clean air as there is no or very little oxygen.