Component Location
General Description
The catalyst’s efficiency is demonstrated by its ability to oxidize CO and hydrocarbon emissions. The Powertrain Control Module (ECM) 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 CO2with 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
If amplitude of B1S2 is different from the model value during 60 sec under enable conditions, ECM sets DTC P0420.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Oxygen storage capacity (Deterioration ofCatalytic efficieny)
| Exhaust system B1S2 Catalystconverter |
Enable Conditions | Engine speed 1600~2480rpm
Engine load 26~50 %
Catalyst temp.(model) > 540?
Purge factor (high load canister) < 1.4
Closed loop control
There is not misfire
There is not malfunction on HO2S / PCSV / ECTS
|
Threshold Value | Difference of ‘amplitude of downstream O2 sensor’ and ‘amplitude of model signal’ > 0.6
|
Diagnostic Time | 65 sec.
|
MIL ON Condition | 3 driving cycle
|
? B1S1 : upstream oxygen sensor / B1S2 : downstream oxygen sensor