A technician is viewing a scan tool data stream to diagnose an OBD II system. The downstream HO₂S has the same voltage switching rate as the upstream HO₂S. Technician A says the air/fuel ratio is too rich. Technician B says the catalytic converter may be defective. Who is correct? A) A only B) B only C) both A and B D) neither A nor B

Question

Quizplus · Accepted Answer

If the downstream HO2S (oxygen sensor) has the same voltage switching rate as the upstream HO2S, it indicates that the catalytic converter is not effectively reducing emissions, suggesting it may be defective. Technician B is correct.

A Technician Is Viewing a Scan Tool Data Stream to Diagnose