Catalyst Monitor
OBD System Description - Catalyst MonitorSystem Description / Monitoring Procedure
ECM calculates the oxygen storage capacity of TWC and monitors the ability of TWC to convert the exhaust emission effectively.
ECM calculates the oxygen storage capacity under specified driving conditions as follows.
1. ECM commands the fuel status to rich (air/fuel ratio: low) until all oxygen is released from the TWC.
2. ECM commands the fuel status to lean (air/fuel ratio: high) until any one of the following conditions is met, and ECM calculates the oxygen storage capacity of TWC by HO2S-2 sensor output signal and duration.
- Saturation of oxygen in the TWC is detected by output signal of HO2S-2.
- Before the saturation of oxygen is detected, the lean status of the fuel injection is longer than specified time. (ECM judges that the oxygen storage is higher than specified value.)
Catalyst System Layout
The system has HO2S located upstream and downstream of the TWC on each bank. The layout of TWC and HO2S is described below.
TWC, HO2S-1 and HO2S-2 layout
DTC Description / Detecting Condition / Confirmation Procedure
P0420 / P0430
Refer to DTC P0420 / P0430:N32A. P0420
Catalyst Monitor
Operation
Enable conditions
Typical malfunction thresholds
Mode $06 Data
Mode $06 Data:
