User guide

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Oxygen Sensor Test Results are numbered so that each test result
can be matched to the part of the plot used as a threshold value in
the testing process. See the O2 Sensors section in Appendix B:
Engine Terminology to better understand how an oxygen sensor
affects engine management.
Also, like the Live Data Graph, adding a sensor to the graph is
easy, select the sensor from the O2 Sensors list above the O2 Sen-
sors graph, or left- or right-click on the graph area and select the
sensor from the drop-down list.
If you no longer need to watch a sensor you can remove it from
the graph by selecting Off in the Live Vehicle Sensor list, or by
right-clicking the graph area and selecting Off.
Post catalytic convertor O2 sensors may not report
fuel trim. It may report as 99.06. In this case, you
will be required to use only the voltage.
Understanding O2 Sensor Locations
Oxygen sensor locations are not universal for all vehicles.
First, you must understand that you can have up to two banks
(B1 and B2) on your vehicle. You will have an exhaust pipe
for each bank; if your vehicle has two exhaust pipes, it will
have two oxygen sensor banks. Sensors are designated with
S1 - S4. Sensor S1 is always before the catalytic convertor
and considered a pre-catalytic convertor (pre-cat.) oxygen
sensor. Typically all oxygen sensors S1 and S2 will be pre-
cat. and sensors S3 - S4 are post-cat. sensors. In the case
where the vehicle only has oxygen sensors S1 and S2, S1
will be pre-cat. and S2 will be post-cat.
Pre-catalytic convertor oxygen sensors should exhibit a
waveform with switching similiar to the example on the O2
Sensor window. Post-cat. sensors should exhibit a low-
amplitude, or semi-flat, waveform while the vehicle is at idle.
Oxygen sensor readings will be inaccurate if the fuel system
is "Open". Data will only be valid if the fuel system is
"Closed". Depressing the fuel while sampling any oxygen
sensor should increase the frequency of the switching.