System Description/Monitoring Procedure

WARNING: This page is about a different car, the 2010 Suzuki Kizashi. However, it is still accessible from the selected car via links, so may be relevant.

Exhaust oxygen concentration at the upstream and the downstream of WU-TWC is detected from A/F sensor and HO2S respectively and accordingly ECM controls the closed-loop which then controls the fuel injection volume. If the WU-TWC is in good condition while the above controls are in operation, the output voltage of HO2S is maintained at the specified level. If the WU-TWC becomes deteriorated, the exhaust gas which passed WU-TWC passes HO2S at the exhaust oxygen concentration similar to that of the upstream of WU-TWC without being oxygenated or converted, even when the above controls are in operation. In this way, waveforms of the A/F sensor and HO2S output voltage become alike and the ECM judges the deterioration of WU-TWC by comparing waveforms of A/F sensor and HO2S.