Warm up the engine sufficiently and monitor the current data.

If HO2S current data is low continously(Lean), go to "Fuel supply state" inspection procedure.

If HO2S current data is high continuously (Rich) and intake air is decreased and MAPS current data is lowered, go to "PCSV" inspection procedure.

If HO2S current data is high continuously (Rich) and exhaust gas is too small, remove catalytic converter and check clogging/damage of the catalytic converter.

If HO2S current data is high continuously (Rich) and excessive exhaust gas, check vacuum hose leakage and intake manifold.