Vitara JX (2Dr) 4WD L4-1.6L DOHC MFI (1999)
Oxygen Sensor: Description and Operation
CIRCUIT DESCRIPTION
Exhaust oxygen concentration at the pre-TWC and the post-TWC is detected from HO2S-1 and HO2S-2 respectively and accordingly ECM (PCM)
controls the closed loop which then controls the fuel injection volume. While the above control is going on and if TWC is in good condition, the
output voltage of HO2S-2 is maintained at specified level. As TWC becomes deteriorated, even when the above control is going on, the exhaust gas
which has passed TWC then passes HO2S-2 at the exhaust oxygen concentration similar to that of the pre-catalyst without being oxygenated or
converted. Thus, waveforms of HO2S-1 and HO2S-2 output voltages become alike. ECM (PCM) judges deterioration of TWC by comparing
waveforms of HO2S-1 and HO2S-2.