Component Location
General Description
The catalyst’s efficiency is demonstrated by its ability to oxidize CO and hydrocarbon emissions. The Powertrain Control Module (PCM) compares the output signals of the front and rear oxygen sensors to determine whether the output of the rear sensor is beginning to match the output of the front oxygen sensor. Air/fuel mixture compensation keeps the frequency of the front oxygen sensor high due to the changes from rich-to-lean combusition. The catalyst causes the rear oxygen sensor to have a lower frequency. As the catalyst wears, the rear oxygen sensor’s signal trace begins to match the front oxygen sensor’s signal trace. That is because the catalyst becomes saturated with oxygen and cannot use the oxygen to convert hydrocarbon and CO into H2O and CO2 with the same efficiency as when it was new. A completely worn catalyst shows a 100% match between the frequency of the front and rear sensors.
DTC Description
ECM controls Air/Fuel ratio by B1S1 monitoring and B1S2 monitoring. By the way, if there is the advanced B1S1 signal line shift compared with the value of B1S2 controller, PCM sets DTC P2096.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | ? O2 sensor characteristic line shift | ? Catalyst converter ? B1S1 ? ECM |
Enable Conditions | ? Dew point end detected ? Required lambda = 1 ? Battery voltage > 10.7V ? Exhaust gas temperature (model) < 800? ? Heater control enabled ? 1200rpm < Engine speed < 3520rpm ? Engine load : 15 ~ 78 % |
Threshold Value | ? The second controller by B1S2 >1sec |
Diagnostic Time | ? 15 sec |
MIL | ? ON |
? B1S1 : upstream oxygen sensor / B1S2 : downstream oxygen sensor
Signal Waveform