Warm up the engine sufficiently and monitor change of HO2S and related current data while accelerating.

If HO2S is not feedback and HO2S is low continuously (Lean), fuel pressure is low.

▶ Go to "Low pressure fuel system" inspection procedure.

▶ Go to "High pressure fuel system" inspection procedure.

▶ Go to "Injector" inspection procedure.

If HO2S is not feedback and is high continuously (Rich), Intake/exhaust system is abnormal.

▶ Check the air cleaner state (blocked, foreign substances) after removing air cleaner.

▶ Check vacuum leakage at intake manifold and vacuum hose.

▶ Remove catalytic converter and check clogging/damage of the catalytic converter.