Discovery I (LJ) V8-4.0L (1996)
/v8-4.0l/Page-970005.png)
The chart will give a graphic depiction of the sensor response and voltages in relation to the setting of P-codes. Note that the response time is measured
between two thresholds. The lean voltage threshold is 3.3 V; the rich is 1.3 V. Set cursors at these two voltages to measure response time.
It is important to note that the fault limits for response time exceeds the typical response observed during a snap throttle test; the higher limits are used by
the ECM to flag codes under normal, not snap throttle driving conditions. The decision to condemn sensors should be based on the chart above.
If there is any doubt about the visual readings from the wave forms, or if exact test results are desired, use the Uniscope cursors to measure the maximum
voltage, minimum voltage, and response time. Most faulty HO2S will be obvious from a visual inspection of the wave forms. Below are some examples
of wave forms.
In this example the rich to lean response time is 124.2 ms. This response time exceeds the 100 ms limit, therefore the sensor should be replaced. Note
